Based on the dynamic identification of the actual metrical load data and the third-order induction motor dynamic model， a generalized induction motor model of the synthetic load is put forward on the basis of simple-point optimum identification strategy. It uses the difference between the actually measured response and the simultaneous basic induction model response as the internal feedback to be added to the model output to form a generalized induction motor model， realizing optimum fitting of the model response and the measurement response. The research results show that the performance of the improved model is better than that of the basic model.