Due to the leaching process is relatively complex, the process model is difficulty to accurately reflect the actual process, the process optimization results based on the model is not the actual optimal value. Based on that, an optimization method of leaching process considering model error is proposed. The method applies Gaussian mixture model to describe the error mean and the error variance of leaching process hybrid model which are brought into the optimization objectives to establish the optimization model of leaching process with taking the process model error into account. Then the second order oscillation particle swarm optimization algorithm is used to complete the solution of the optimization model. Finally, simulation results show the effectiveness of the proposed method.