The invention discloses a test method for improving the generating set leading phase capacity. The method comprises the steps that whether a generating set has a leading phase capacity improvement space or not is analyzed, for the set with the development space, main transformer, high plant transformer and low plant transformer tap configuration is optimized on the premise that the set safety is not affected according to historical operation data of the set, the service power voltage and terminal voltage levels are raised, leading phase testing is carried out in the state that multiple sets operate simultaneously, when testing is conducted, the deep leading phase capacity of the set is obtained by dynamically adjusting the reactive simulation grid reactive power surplus state of a test accompanying set, and the purpose of improving the leading phase capacity is achieved. Accordingly, the set can exert the deeper leading phase capacity in the low load period of the grid, the safe operation level of the grid voltage is improved, and the method has a good application prospect.