A novel directional protective scheme based on model identification method for series compensated transmission lines is proposed. The scheme detects transmission line fault by comparing the model error， inductance and capacitance calculated in two different models. Comparing with the traditional directional protection in frequency domain， instead， the proposed method calculates the parameters in time domain， and mal-operation caused by the compensated capacitor is avoided. Simulation results show that the proposed method is not affected by DC component， fault type， fault location and transition resistance， and it has high accuracy.