This paper examines the evolution of a classical Chinese theater—Kunju. It looks into the history of Kunju by delving into literary documents and related historic records. Originally, Kunju used Kunshan tune, a local music style in Kunshan. Thanks to the contributions of Wei Liangfu and his contemporaries, Kunshan tune was refined into a new music style. This refined tune used official language (guanhua) and the melody was generated in accordance with the tones of the words. Besides, new music instruments were introduced to make vocal delivery more pleasing. These refinements helped Kunshan tune become a national music style before spreading from Suzhou to the rest of China. Kunju stresses on-stage dramatic performance and mimetic movements. This paper also identifies challenges facing this classical Chinese theater.