The purpose of this thesis is to study and analyze Ludwig van Beethoven' Piano Sonata Op.110 in A♭major. As a composer who described men's feeling with creative and innovative techniques, Beethoven influenced the development of the Classicism and opened the way for Romanticism in 19th century. He spent most of his time in composing Piano Sonata among other Piano Solo pieces. His 32 pieces of the Piano Sonata written during hiw whole life disclose the change of his musical style and take an important place of modern keyboard music history. Among the last 5 Sonatas, Op.110 composed in 1822 is made up of 3 movements but less distinctive between each movement and liberated from traditional form to some extent. The first movement(Moderato cantabile molto espressivo, A♭major, 3/4) is of Sonata Allegro form and composed of 'Exposition, Develpoment, Recapitulation, and Coda'. The second movement(Allegro molto, f minor, 2/4) is of Ternary form with trio which consists of 'Scherzo - Trio - Scherzo'. Traditionally the second section has a slow movement but the distinctive feature of this piece is that the trio part has a fast movement. The third movement(Adagio ma non troppo (Arioso dolente) - Fuga - Arioso - Fuga, A♭major, 4/4) has 4 parts which includes 2 Fugas. It is noticeable that this movement has independently introduced the 2 Fugas into Sonata and freed from traditional formalism. The characteristics of the movement are 'repeated use of Diminished chord' and 'Chromatic and Enharmonic key change'. This thesis tracks the trends in 32 Piano sonatas of Beethoven and analyzes the Op. 110 in the technical aspect. This will help the performer play better through the understanding of Beethoven's personality and his spiritual world.