In order to increase the photo-generated carrier density of the photoconductive switche, prolong the service life of the device, reduce the energy requirement of the light source, and realize the miniaturization of the device, we establish a mathematical model of the total internal reflection photoconductive switch based on the semi-insulating 4H-SiC material. The conditions of total internal reflection and the factors that affect photoconductive switches absorption efficiency and uniformity are analyzed. The non-sequential mode in ZEMAX is used to establish a total internal reflection photoconductive switch model, and the ray tracing method is adopted for analysis. A high-efficiency total internal reflection photoconductive semiconductor switches optical system is designed. The results show that the optical system can achieve high absorption efficiency while ensuring high uniformity. The absorption efficiency can reach 90.78% and the absorption uniformity can reach 74.56%.