Due to the existence of the“cream skimming”of the new company, the supply of default service from the original electricity company has become difficult. Based on the analysis of the“cream skimming”, this paper firstly establishs the supply demand function of the original in position power supplier that provids the default service and the new entry power supplier. Then we discuss two mechanisms, the unified pricing of the urban area and the complete marketization of the urban area separately. Finally, the game supply model is established and solve the equilibrium solution of the response. This model has certain referencing value for the rule design of domestic default service under the new round of power system.