Sandwich panels have high strength to weight ratio because of their special structure. The variables which are defined for designing sandwich panels should be determined with applying necessary strength and lowest weight. In this paper, the imperialist competitive algorithm (ICA) has been used for minimizing the weight of a sandwich panel with prismatic core based on yielding and buckling criteria. ICA is inspired of imperialist competitions and it is based on two special criteria as recruitment policy and stable imperialist competition. Arrays numbers, core and surface thickness and panel height are assumed as design variables for decreasing panel weight. The results were shown that core and surface thickness and the total height of panel has been increased by increasing loading for given number of arrays. Also the core and surface thickness has been decreased and the total height have been increased by increasing array number for a determined loading and so panel weight has been decreased. A panel with diamond core has highest structure efficiency. It was shown that ICA is useful and competitive than the other heuristic algorithms because of direct using of function values in some problems which was required to the total optimization.