Beethoven’s Piano Sonata Op. 90 represents the pinnacle of his compositional achievements during his middle period, showcasing significant transformations and advancements in his musical style. This paper analyses the structure and technical features of Piano Sonata Op. 90, including its two-movement sonata, the treatment of thematic material, and the application of polyphonic techniques. These elements illustrate the stylistic evolution from Beethoven's middle to his late periods. A detailed musical analysis of Piano Sonata Op. 90 reveals how Beethoven integrated classical and Romantic elements within this work, thereby foreshadowing the technical and spiritual developments of his late period compositions. Furthermore, the paper discusses specific performance techniques essential for interpreting Piano Sonata Op. 90, providing practical guidance to enhance understanding and execution of this masterpiece.