In order to study the effects of single-junction GaAs photovoltaic cell irradiated by 808 nm continuous wave laser, a physical model was established by software COMSOL and MATLAB. The voltage-current characteristics, open circuit voltage, short circuit current, photoelectric conversion efficiency, fill factor and heat steady temperature of cell were simulated, and the influence of the power densities, equivalent series, parallel resistance and antireflection coating were also discussed. The results shows that open circuit voltage and short circuit current increases with the increase of laser power density, while conversion efficiency and fill factor have maximum value. Reducing equivalent series resistance and increasing equivalent parallel resistance are an effective method to improve the output performance of cell. It was significant to improve the efficiency of cell with adding antireflection coating, however making the cell temperature higher at heat steady. The conversion efficiency of cell reaches to maximum value of 50.13% under 62.4 mW/cm2 at heat steady. The simulation result is basically consistent with relevant experiments, which can provide theoretical reference for output characteristics study of photovoltaic cell by continuous wave laser irradiation at some extent.