SiC PCSS is a research hot spot in related fields. However, theoretical research on 4H-SiC PCSS in the literature is still based on lumped element models that can only provide qualitative results. A quantitative explanation of the experimental data under transient conditions in typical literature is still lacking. This study uses the device-circuit hybrid mode in Silvaco TCAD software to simulate the optical and electrical characteristics of the 4H-SiC PCSS combined with a self-written carrier mobility interface program. The simulated results of the single pulse response show that the variation in the peak photocurrent of the device with optical energy is in good agreement with the experimental data under transient conditions reported in the literature,indicating that the model and parameters used are reasonable. The study also calculates and analyzes the main factors that affect the single pulse response, including the pulse energy, pulse width, and silicon carbide thickness. The multi-pulse responses of the devices for the two 4H-SiC thicknesses are calculated and analyzed. The results and conclusions obtained in this study provide a good reference for further research on SiC PCSS