Urban-rural integration development is the inevitable requirement of Chinese modernization. As an important part of the national governance system and the core content of China's independent knowledge system of auditing, national audit should empower the urban-rural integration development in the process of serving the Party and the country's major strategy. Based on the latest Spirit adopted by the Third Plenary Session of the 20th CPC Central Committee and the need to build an independent knowledge system of auditing in China, this paper discusses how national auditing can help coordinate new industrialization, new urbanization and overall rural revitalization, and finally promote the integrated development of urban and rural areas. Based on the panel data of 30 provincial administrative regions in China from 2011 to 2023, this paper constructs a two-way fixed effect model to investigate the influence effect and mechanism path of national audit on urban-rural integration development. It is found that the national audit has significantly promoted the development of urban-rural integration, especially in areas with a high degree of digital economy and opening to the outside world. New industrialization, new urbanization and comprehensive rural revitalization are the key mechanisms for the national audit to promote the development of urban-rural integration. The research conclusion provides new theoretical support and practical ideas for the national audit to effectively promote the integration of urban and rural development, and also provides solid empirical evidence for the construction of independent knowledge system of auditing in China.