The invention discloses an air cooling system guide plate shape optimization method for battery thermal management. The method comprises the following steps: starting from uniform main runner sectionwidth distribution, carrying out numerical solution on the cooling runner flow of an air cooling system, starting from a cooling runner far away from an inlet or an outlet to the direction of the inlet or the outlet, and selecting the runner section width which enables a system objective function to be optimal by sequentially adjusting each main runner section width; assuming that the section width of each main runner is adjusted once as one round, and through repeated multi-round adjustment, continuously approaching the optimal section width distribution; when the target function value does not change in one round of adjustment, regarding the main runner section width distribution corresponding to the optimal target function value recorded in the adjustment process as the optimal distribution; and finally, obtaining a final smooth guide plate shape through polynomial fitting according to the obtained optimal section width distribution. The method has the advantages of being simple inoptimization process, good in performance index, good in expansibility, high in practicability and the like.