The invention discloses an improved strategy of an aeroengine fuel metering system and a designing method of a controller thereof. By ways of adjusting component structure of a differential pressure controller and increasing front and back differential pressure of a metering valve to be a new control variable, a traditional constant-differential-pressure flow metering device is changed into a novel variable-differential-pressure fuel metering device, and expected fuel flow is controlled by the front and back differential pressure of the metering valve and the flow area; the maximum flow range is increased according to the variable-differential-pressure fuel metering system and the requirement on precision is improved. The differential pressure of the metering valve adopting a step control mode is proposed, the flow area adopts a double-variable control rule in a stepless control mode. Under the requirement of mass flow of the aeroengine, by approximately increasing the differential pressure value, under the condition of current maximum flow area, the larger fuel flow can be obtained, and the metering range of the fuel flow is widened; under the requirement on minimum flow, under a condition of a fixed structure of a metering valve type hole, by reducing the differential pressure value, the flow gain is reduced, and the metering precision of the system is improved.