Based on integral equation theory, the structure of the blackbody cavity model was established. Analyzed the length to diameter ratio of cavity, the aperture ratio, the distance between the aperture and the receiver, the cavity material itself emissivity and other factors that have influence on the cavity emissivity, and the optimization parameters of the blackbody cavity was designed, at the same time the finite element analysis method was used to analysis the influence of different shapes of blackbody cavity on the receiver steady temperature and the dynamic response time. The result shows that the change of the blackbody cavity structure parameters have direct influence on the blackbody cavity emissivity, the receiver steady temperature, and the dynamic response time, and then affects the performance of the blackbody cavity, and the method of the combination of the finite element method and integral equation method analysis provides a new idea for the study and optimization design of the blackbody cavity.