Based on the analysises of the measured bidirectional reflectance distribution function (BRDF) data and the limitations in Phong model, a modified model is proposed to describe the Fresnel reflection properties. On the basis of the classical Phong model, two parameters are added to adjust the strength and the decay rate of Fresnel reflection in different materials, respectively. The genetic algorithm is used to fit the BRDF data from 4 kinds of commonly used materials for space targets, and the fitting errors of the modified model and the classical Phong model are compared and analyzed. The results show that the fitting precision obtained by the modified model is 90% higher than that obtained by the classical Phong model for the materials with an obvious Fresnel reflection phenomenon, which verifies the effectiveness of the modified model. For the materials with a weak Fresnel reflection phenomenon, the fitting errors obtained by the two models are equivalent, which represents the robustness of the modified model. The modified model can better describe the Fresnel reflection phenomenon while keeping the orginal excellent description ability of the Phong model.