The laser radar cross section (LRCS) of complex target is a very important parameter in laser acquisition and stealth all the time. The theoretical method of calculation of LRCS is comparatively mature,but in the overall combination design of target modeling, target surface coating materials and LRCS calculation integration, there are still some problems remaining to be solved.Aiming at this problem, we introduce anapplication integration developing method of complex target′s (coating material) calculation of LRCS based on Unigraphics modelling software, model of bidirectional reflectance distribution function (BRDF) and graphical electromagnetic computing (GRECO). The program′s application integration design is effective, proved by calculation examples based on this method, besides, this method has high precision and accuracy in computing.