To improve the solving efficiency of computer aided conceptual design (CACD) systems, this paper proposes a novel heuristic planning approach for automated conceptual design synthesis based on the idea of automated planning in artificial intelligence. The proposed method represented the functional knowledge of principle solution based on the stateaction method. With the proposed three integrationsolving search strategies (e.g., forward chaining integration, backward-chaining integration and forward-backward-chaining integration), the proposed methods can efficiently solve design problems. Finally, a design case of tidal power system illustrates that the proposed heuristic planning approach can successfully achieve an automated conceptual design synthesis.