The single-ended traveling wave fault location method needs to extract the time-frequency domain characteristics of the fault traveling wave when considering the influence of frequency-dependent wave velocity. However, existing methods have low time-frequency resolution, difficulty in identifying the wave head, and inaccurate calculation of wave speed. Therefore, a single-ended fault location method based on parameter-optimized variational mode decomposition (VMD) and transient extraction transform (TET) is proposed. First, the VMD parameters are optimized using the sparrow search algorithm (SSA) to extract the high-frequency modal components containing fault features. Then, a time-frequency analysis method based on transient extraction transform is proposed. This removes the ambiguous time-frequency energy in the short-time Fourier transform and only retains the time-frequency information closely related to the transient characteristics of the signal, accurately extracting the time-frequency characteristics of the fault traveling wave. Finally, this paper extracts the main frequency component of the fault traveling wave full waveform and calibrates the initial wavehead and the second reflected wavehead, and calculates the wave velocity under the main frequency component, so as to realize the single-ended fault location. The simulation results of a four-terminal flexible DC grid built in PSCAD/EMTDC show that the proposed algorithm has strong tolerance to transition resistance and noise, and can achieve accurate fault location even at low sampling rates.