Abstract: In the environment of Smart Grid, the integration of various demand response programs will have significant influences on the market participants’ strategic behaviors and the overall electricity market competition outcomes. Assume that the flexible consumers are allowed to take part in the wholesale electricity market competition in the form of demand response aggregators, the Cournot equilibrium model is build. Load shifting and curtailing programs can be incorporated at the same time by a special constraint. The nonlinear complementarity approach is used to solve this equilibrium problem. Numerical examples show that: The DR resource joined the market competition can effectively encourage the flexible consumers to shift the load from peak-periods to off-peak-periods, and reduce the gap between peak and valley. For DR aggregators, the DR aggregators with load shifting and curtailing resources are more competitive in the wholesale electricity market.