The laser response of HgCdTe medium-wave photovoltaic device is numerically simulated in this research. The simulations are carried out by considering the carrier electrical properties and a simulation model is obtained, and simulation results are in general conformity with the experimental results under both strong and weak illumination. The saturation threshold increases as the operating temperature of the device decreases, according to the current response characteristics of the device. The contact resistance of device is calculated and discussed, and the optimized device structure are given to point out the direction of parameter optimization. Furthermore, two-dimensional simulations demonstrate that the electrode size and composition gradient and reverse voltage has a considerable impact on the photocurrent, which is an essential problem to address in the development of high saturation threshold mid-wave infrared HgCdTe photovoltaic devices.