Aiming at the difficulty in estimation of harmonics caused by nonlinear dynamic loads, this paper proposes a new method of harmonic estimation. First the algorithm utilizes the global searching capability of the CPSO to optimize the unknown parameters, then the optimized output of CPSO is taken as the initial values of weights for RLS algorithm, and finally the weights are updated using the steps of RLS algorithm. Through the experiment simulation, compared with CPSO algorithm, the maximum estimation accuracy of harmonic amplitude and phase is enhanced about 7% and 1. 24% respectively. The simulation results show that the proposed algorithm can ensure convergence speed, and has higher estimation precision.