Applying to neo-institutional economics' supply-demand analytical method, this article makes empirical analysis for the supply and demand conditions of China athletes' social security system. The result shows China has initially established the framework for athletes' social security system which fits market economic system and the Whole-nation System of competitive sports industry; the most notable factors to influence the demand of social security system are the income level of top athletes, the address and risk awareness. In the critical period to construct atheltes' social security system, this article advises to further improve institutional system to achieve supply and demand balance of atheltes' social security system by perfecting system design, solving the historical problem, developing social insurance and implementing active employment policies.