Aiming at the problems existing in fault location of HVDC transmission line, such as long transmission line, high fault probability, low fault location accuracy and noise in fault waveform, a fault location algorithm for HVDC transmission line based on VMD decomposition and generalized S transform is proposed. Firstly, the traveling wave signal with noise is decomposed by Variational Model Decomposition (VMD), and the noise is filtered to obtain the optimal modal component. Then, the Generalized S-Transform (GST) is used to calculate the optimal modal component, and generate the S-matrix with high temporal resolution. And then the high frequency component in the S-matrix is selected, the waveform mutation point of the frequency component is identified, thus, the arrival time of the initial traveling wave of the fault can be obtained. Finally, the fault distance is obtained by the formula of fault location. PSCAD/EMTDC simulation results show that the proposed method is less affected by the transition resistance and has high accuracy in fault location with different fault distances. Through the verification of field fault traveling wave data, fast and accurate fault location can be achieved in the line range. This work is supported by Key Laboratory Project of Liaoning Province (No. LJZS003).