With the increasement of signal frequency and PCB wiring density, the effect of PCB via structure on signal integrity is more and more obvious. The rationality of via design can greatly affect the transmission quality of PCB signal. Based on SIwave and Designer simulation software, the PCB structure model for differential via analysis is established. According to different via radius, pad size, antipad size, via length and whether it has a stub, nonfunctional pads, the S parameters in the frequency domain are extracted respectively and the TDR waveforms of the corresponding time domain are obtained. The influence of via structural parameters on the transmitted signal is analyzed in a comprehensive way, and suggestions on the PCB via design are proposed. Through the analysis of via on the differential line of actual PCB, the rationality of the proposed via design is verified.