This paper analyzes the promotion mechanism of service FDI to economic growth, and makes an empirical research on the relationship between service FDI and economic growth, with Guangdong as example. The results of the study show that service FDI has positive effects on the economic growth of service industry, and these positive effects are exerted through industry agglomeration effect, public service creation effect and service trade effect. Moreover, because there is still much room to improve the promoting function of domestic investment to service economy, government should attach great importance and enhance the role of domestic investment on development of service industry, realizing synergy drive of foreign and domestic investment on service economy.