Shock response spectrum technology is the important technical means for simulating complex impact environments in laboratory environment, so it is important to study the synthesis timedomain waveforms of shock response spectrum. The relative displacement model of the shock response spectrum was constructed. The shock response invariant method was used to design the digital filter, and the calculation of shock response spectrum was completed.Taking the sinusoidal fundamental wave as the basic waveform of the synthetic fundamental,the expressions of the fundamental waveform parameters were determined, and the amplitudes were corrected by iteration. The simulation results show that the shock response spectrum calculated by using the above method can meet the requirements of the test specification within the tolerance range of the target spectrum. The method can be widely used in shock test and has certain promotion value.