Self-efficacy refers to the hypothetical inference made by individuals about whether they can complete a specific behavior or task. Therefore, learners’ positive self-efficacy will positively impact on their learning behaviors and results. In order to explore the relationship between English Majors’ self-efficacy and English achievement, this study designs questionnaire to investigate the English Major juniors in NingboTech University. Based on the data collected from the questionnaire, this paper tries to analyze the overall level of self-efficacy of English majors and probe into the relationship between English majors’ self-efficacy and their English achievements. After analyzing the data by SPSS 26.0, the following results are obtained: (1) The respondents’ self-efficacy is at a medium level; (2) There is a significant positive correlation between the respondents’ English self-efficacy and their academic achievement, and the former can predict the latter. In view of the research results, this study puts forward some suggestions for teachers to improve students’ self-efficacy in order to enhance students’ learning effect in the teaching process.