Abstract: Based on Baumol's theory of unbalanced growth, this paper uses the method of transformation share analysis to carry out empirical tests, and constructs a three-sector analysis model to study the promotion of tertiary industry to economic growth. The results show that in the early and middle stages of industrialization, the agricultural population has shifted to industry and service industry, and the increase of the proportion of service industry in the industrial structure has promoted economic growth. In the latter stage of industrialization, the development of industrial technology squeezes out the labor force, the population is forced to transfer to the service industry, and the expansion of the share of the life service industry inhibits economic growth. However, if the share of the service industry with the producer service industry as the main body expands, it can promote economic growth.

Key words: the proportion of tertiary industry, economic growth, the effect of structural change, the effect of technological progress