Urban agglomerations are the main spatial carriers of China's economic development. Accelerating high-quality economic development in western urban agglomerations is of great significance for narrowing the development gap between the east and west of China and achieving regional coordinated development. The paper takes 9 urban agglomerations in the western region as the research object, constructs an evaluation index system for the high-quality economic development level of western urban agglomerations in China, and measures it. At the same time, based on five dimensions of economy, society, system, population, and environment, it identifies the main driving factors that affect the high-quality economic development of western urban agglomerations. The results indicate that the overall high-quality economic development level of the western urban agglomeration is showing a slow growth trend; There is a significant difference in the high-quality development level of subsystems, with a significant gap between the coordinated development level and the green development level, and the smallest gap in the open development level; The improvement of investment level, consumption level, transportation level, wage income level, and environmental governance level can significantly promote the high-quality development of the western urban agglomeration economy. The degree of government intervention and population agglomeration have suppressed the high-quality development of the western urban agglomeration economy, and various influencing factors are heterogeneous. Based on this, the western urban agglomeration should further fully, accurately, and comprehensively implement the new development concept, and enhance the high-quality economic development level of the urban agglomeration; Adhere to problem oriented approach and accelerate the filling of shortcomings in urban agglomeration development; Optimize resource allocation and promote the integrated development of urban agglomerations.