This study seeks to investigate the modern derivative of Beijing opera, known as yangbanxi, through macro and micro approaches. The first part of the thesis surveys the development of Beijing opera under the historical context and in its social, political, and cultural perspectives. The second part, taking a microscopic perspective, undertakes an in-depth analysis of the compositions that were solely created by composer Yu Huiyong. First, it assays the application of Yu’s theory to his compositions of various Beijing opera arias. Second, it analyzes Yu’s instrumental music in compositional dimensions such as material, structure, and techniques, considering the larger implications of Yu’s approach. Third, it explores the highly acclaimed opera Azalea Mountain as a case study, integrating compositional analysis and sociopolitical perspective in order to give a relatively full picture of Yu’s final work as sole composer. The analysis also focuses on three aspects of the yangbanxi. The first aspect is the role of composers, in which Yu Huiyong was largely responsible for shaping the musical language and influencing the direction of Beijing opera. The second aspect is the role of politics, focusing on Jiang Qing, who had a clear vision to transform Beijing opera along revolutionary lines and the artistic and political wherewithal to implement that transformation. The third aspect is the role of culture in shaping society, with an emphasis on yangbanxi, as the artistic centerpiece of the Cultural Revolution, and special consideration is given to its role in creating a new mass culture. Beijing opera, as a living art form, had been undergoing a process of modernization throughout the first half of the twentieth century, but it was Yu Huiyong who clearly articulated what needed to be done to make the traditional art form relevant to modern audiences. In particular, the most significant achievement of yangbanxi was its music development, which achieved a new height in artistic development thanks to Yu Huiyong’s fully constructed music theory and newly established music and performance system. As the main composer, designer, theorist, and organizer of yangbanxi, Yu Huiyong made the greatest contribution to these developments. His academic research laid the theoretical framework of the further development of opera music, and his hands-on practice and music innovation provided valuable experience for the younger generation.