The present invention provides a machining method of a valve hole and the valve hole machined with the method, wherein the method includes the following steps: (1) performing drilling machining for a valve hole by adopting a valve hole drill bit to achieve a predetermined machining dimension; (2) performing fine machining by adopting a reamer to allow the diameter of the valve hole to reach a stable dimensional state and removing impurities and aluminum scraps on the surface of the valve hole, thereby meeting the requirement of final fine grinding extrusion machining for a blank; and (3) performing final precision machining by adopting a grinding extrusion tool. A technical solution of the present invention can improve the machining precision and strength for the valve hole, prevent the generation of hot cracks and improve the anti-fatigue strength of the valve hole by more than 20%.