Abstract: This paper draws on the research results of Beijing's "non-capital function" to define the functional connotation of non-capital city functions with the theory of urban function and the principle of spatial economics. It also analyzes the functional problems of non-provincial cities in Chengdu according to the conceptual connotation of non-provincial city function, and quantitatively analyzes and identifies Chengdu's urban functions with the Maxwell's urban function classification method on the basis of Nelson's method. In the comprehensive consideration of Chengdu's provincial capital and the city's functional positioning, it identifies the non-provincial functions of Chengdu, and finds out that the non-capital city functions of Chengdu focus on general manufacturing, whole sale and retail, education and medical industry. In view of the problem of functional relief in Chengdu's non-capital cities, this paper proposes the following five countermeasures: promote the suburbanization of some non-capital cities functions, promote coordination within the urban agglomeration of the Chengdu Plain, promote the transfer of some provincial and municipal administrative departments, promote the reorganization of industrial functional departments, and create a "Tianfu-characteristic" high efficiency urban transportation system.