The invention discloses a multi-material fused light high-strength battery pack structure and a design method thereof.The multi-material fused light high-strength battery pack structure comprises a bearing frame, battery modules, an upper cover and a plug board, a cooling plate is arranged at the upper end of the bearing frame, the battery modules are arranged on the upper surface of the cooling plate, partition plates are arranged between every two adjacent battery modules, and first grooves are formed in the partition plates; a first partition strip is arranged in the first groove, the first partition strip divides the first groove into a continuous S-shaped first flow channel, the first flow channel is communicated with a first water inlet pipe and a first water outlet pipe, a first heat conduction metal plate is sealed in the first groove, the upper cover covers the battery module, and the plug board is matched with the upper cover for use. And the upper cover, the cooling plate and the plug board form a closed cavity. According to the bearing frame, the strength needed by the battery pack is guaranteed while the battery pack is lightened through the frame type structure, the battery module is wrapped by the upper cover, the plug board and the cooling plate, the sealing performance of the battery module is guaranteed, and the bearing frame has the effects of being simple in structure and low in cost.