To qualitatively describe the weak characteristics of surrounding rock, an inversion method for seismic velocity curve based on transient electromagnetic resistivity is proposed. The specific steps are as follows: (1) The characteristics of tunnel seismic data are analyzed in detail, and the reverse velocity stack method is proposed to extract stack gather, so as to reduce the error of single channel waveform and improve the inversion accuracy in the later stage. (2) The tunnel seismic wave impedance inversion method is proposed to calculate relatively reliable velocity curve in the advance direction. (3) To overcome the multisolution problem in velocity inversion, the relationship between velocity and resistivity is established according to the Faust formula. The apparent resistivity data provided by the TEM is converted into the initial velocity model to improve the precision of wave impedance inversion. The inversion results of the model data prove the rationality of the inverse velocity stack method and the importance of the initial velocity model. The inversion results of the measured data show that the velocity inversion curve with apparent resistivity constraint can better improve the inversion accuracy of the velocity curve in the advance direction. Later excavation results also verify the rationality of the velocity curve.