Abstract: A new optimization design method for principle scheme based on directed graph is proposed for the design of principle scheme of cooling system in electric transmission armored vehicle. The simplified models of thermal parts, radiator and pump are established. Basic rules of using directed graph to represent the principle scheme of cooling system are put forward. A practical example is used to verify the proposed method, which indicates that, compared with the principle schemes of which all thermal parts are assembled in parallel and which all thermal parts are assembled in series, the fitness function value of the optimized scheme is reduced by 62.6% and 54.5%, respectively. This research has a certain reference value for the design of principle scheme of cooling system.

Key words: ordnance science and technology, electric transmission armored vehicle, cooling system, design of principle scheme, directed graph