The LiDAR based on single-photon avalanche diode (SPAD) is widely used in 3D perception due to its advantages of high sensitivity, long detection distance and high integration level. The LiDAR system based on SPAD contains various sub-modules, and studying the influence of different types of sub-modules on the performance of LiDAR system can help optimizing the system scheme, improving R&D (research and development) efficiency, and reducing R&D cost. Therefore, according to the feature of sub-modules, we use the time-correlated single-photon counting technology (TCSPC) and the Monte Carlo method to establish the LiDAR model based on SPAD. The effects on system performance of passive reset circuit and active reset circuit, single-event first-photon TDC (time to digital converter) and multi-event TDC are obtained. The results show that the system performance of the active reset circuit and the passive reset circuit is basically the same under the conditions of the time of fight of 20 ns, the ambient light of 50×10³ lx, and the target reflectivity of 10%. After the target reflectivity increases to 50%, the system performance of the active reset circuit is better than that of the passive reset circuit. Similarly, the system performance of multi-event TDC is better than that of single-event first-photon TDC, mainly because the noise of multi-event TDC is uniformly distributed, and compared with single-event first-photon TDC, the peak value of signal count of multi-event TDC is more likely to be greater than the peak value of noise floor count, and the corresponding solution range algorithm is simpler and requires less computing power. The simulation results show that in order to optimize the system performance, the sub-module of the SPAD integrated chip should adopt the architecture of active reset circuit and multi-event TDC.