The invention discloses an aircraft piston engine load coordinating and controlling method. The method is based on an engine load coordinating and controlling system. The engine load coordinating and controlling system comprises an FADEC control system, an electronic throttle body and an electric propeller pitch changing system, wherein the electronic throttle body and the electric propeller pitch changing system are separately connected with the FADEC control system; and the FADEC control system comprises a measurement sensor, a controller and an actuator. The sensor is used for measuring the rotating speed of an engine, the position of an operating lever, and parameters of the percentage of an electronic throttle. The electric propeller pitch changing system is used for mechanical decoupling of the operating lever and the rotating speed of a propeller; and the electronic throttle body is used for the mechanical decoupling of the operating lever and the percentage the throttle valve. The actuator is used for realizing oil injection and ignition of the engine. According to the method, an optimal algorithm is figured out through the operating condition of the engine based on a request for flight thrust power, so that an operating point is obtained through calculation; the expected throttle percentageand the rotating speed of the propeller at present are determined; and the throttle percentage and blade angles are adjusted through a closed-loop control system.