After Western opera was introduced to China, Chinese composers gradually integrated traditional Chinese music and Western music, and gave full play to the characteristics of Chinese folk music. In the early days, the name of " the National Opera of China" established a Chinese opera that was completely different from Western opera. Based on the form of "Yangge" in Chinese traditional music, the first few representative operas were created. After the drastic changes in social development, China's door opened, and the development of national operas also underwent earth-shaking changes."Regret For The Past" is the earliest lyric folk opera in China. In 1981, Chinese composer Shi Guangnan composed music based on the novel of the same name by Lu Xun, a modern Chinese writer and thinker. In the era of reform and opening up, a series of new values in China began to emerge slowly, comparing the love development of the hero and heroine to the changes of the seasons, and showing the conservative feudal traditional concepts and the pursuit of individual freedom by the new young intellectuals at that time. Contradictions and conflicts, but due to the influence of the general environment, the tragic ending of failure on the road to self-worth. As an Enlightenmentist, Lu Xun believed that improving the ignorant national consciousness at that time and breaking the old feudal habits was the only way for the country to get out of the predicament, which directly or indirectly reflected this idea in his works. Judging from the operas composed of such novels as materials, the materials of national operas are diversifying.Composer Shi Guangnan combined Western compositional techniques and traditional Chinese music to present an original national opera standard. Rich and colorful timbres, dramatic plots with conflicts, and delicate musical performance are important features of Western opera. Composers use various forms of arias such as chansons, ballads, and romances, and appropriate elements of traditional Chinese music. Use the elements of Western music to maximize the dramatic effect. The main motive of Juansheng's first aria "She Takes My Heart" is transformed into multiple forms, performing a lyrical melody, calling Zijun's name repeatedly, expressing his anxiety for her. If you look at the accompaniment, you will think of the breeze blowing in the intro, and the lyrics and vocal melody are emphasized in the blank space of the accompaniment, and the main theme of the main melody is used in the vocal melody. The accent is used at the end to make the anxious love more strongly expressed.The second romantic song "A Ray of Setting Sun" by Zijun is generally low-pitched, with almost no melody jumps. The melody does not directly express his psychology, but indirectly uses the rhythm pattern and sound form of the accompaniment to express his desire to escape from the feudal society and The will to love freely. The third song Zijun's chanson "Joyful Waiting" is characterized by the transformation and flexible use of the main motive and accompaniment pattern compared to the use of many elements, and a compact structure. This is a song that effectively expresses Zijun's joy and excitement through concise rhythm and melody, accompaniment patterns, and artistic styles such as ornamental sounds and vibrato.The fourth is a lyric song "The Road of Life is Difficult" by a male singer. Compared with vocal melody, the proportion of accompaniment is greater. In the prelude, the strong autumn wind and the scenes of Zijun and Juansheng suffering from life are described with music using beat, speed, rhythm, and sound pattern. Although the accompaniment of this piece is more effective, when the vocal melody is complex, the accompaniment gives the audience a pure feeling.The fifth aria "Life, Life" is Juansheng's romance song. The prelude begins solemnly with bass melody, creating a heavy and depressing atmosphere. The main motive is used in the prelude, emphasizing the emotional part. According to the content of the lyrics, the melody also changes accordingly, but the running through of the main motives gives a sense of unity. The ending ends in the solemn atmosphere created by the prelude.The common feature found in the five arias is formal structure. It is not based on the two-sentence structure of the aria, but changes according to the content of the lyrics, allowing it to proceed freely. That is, it is not a 2-sentence or 4-sentence expression like Western classical music, but a free expression that is not limited by the number of bars. That is to say, a free expression is formed by adopting a method that can effectively convey lyrics without sticking to a formal framework.In terms of harmony, based on the traditional five-mode, seven-mode, complete four-degree harmony or complete five-degree harmony, combined with the composition of Western music modes, colorful harmony changes are derived.It can be seen that the opera "Regret For The Past" reminds the standards of Chinese national operas, and at the same time, it is also a work that requires a change of consciousness, and has musical and social value. Beginning with the lyrical national opera ""Regret For The Past ", operas embodying the fusion of Western music and Chinese folk music have come out one after another. Lament for the Past has also become one of the most widely performed and well-known opera works. While inheriting the Chinese national characteristics, Chinese national opera is also connected with internationalization and has developed into an opera that keeps pace with the times. The national of China’s opera "Regret For The Past" studied in this thesis not only provides clues to the solution of the current problems that Chinese national opera should overcome, but also hopes to provide some reference for scholars who want to perform this work.