Aiming at the problem of the randomness, anti-peaking and low prediction accuracy of renewable energy sources, this paper presents a method for chance constrained economic dispatch (CCED) problem in power system including renewable energy sources (RES), of which the error of the forecasting results of RES’s output from the true value is taken as random variables, and the probability constraints of the operation limits is considered. A CCED model of the power system including RES is established with the minimal generation cost expectations as the objective. According to the characteristics of the probability constraints, a second-order cone programming (SOCP) description of CCED is firstly constructed, thus transforming the original probability constrained optimization problem into the deterministic optimization problem, and then, the problem is solved by interior point method. The numerical results obtained by IEEE-30 bus systems verify the feasibility and validity of the proposed model and method.