Fault location identification of highvoltage transmission line, especially threeterminal lines, is an important issue in power system operation. In this paper, we investigate the application of wavelet transform to locate the fault position of teed circuits high-voltage transmission line. The components of the transient wave at terminals of the faulted line are simulated by MATLAB Simulink. These components will be decomposed into wavelet coefficients by using discrete wavelet transformation. The proposed approach has the advantages that gives the exact time of transient wave for traveling from fault position to the terminals of the lines. To evaluate the applicability and effectiveness of this new approach, we have applied the proposed method to a threeterminal transmission line in reference [9] and the actual transmission line 110kV O Mon – Sa Dec – Binh Minh.