This paper establishes a three-stage principal-agent model to analyze the decision-making mechanism of producing services,and then uses ordinary least squares and instrumental variable approach combining with the 2012 data of Chinese provincial services sub-sectors and drawing on difference-in-difference method to study the relationship between contractual environment and services output & producer services output.The empirical results show that the contractual environment is an important factor affecting services output,and there is a higher level of services output in the more privileged areas of contractual environment,because a better contractual environment can help to maintain normal execution of contracts and guarantee service enterprises enthusiasm for production.And this role in a high dependence of services on contracts is more obvious.It draws the same conclusions in testing the sample of producer services.The previous results are still robust after controlling a series of factors such as human capital,physical capital,trade liberalization,investment in industrial infrastructure,and the level of regional infrastructure development.