The invention discloses a valve body machining method. The valve body machining method comprises the following steps that firstly, a valve body blank is inspected, specifically, all final inspection is conducted on the blank before a machining stage, and shape misalignment, rough surfaces and unevenness which are generated due to the reason of casting and casting interior material loose defects are not allowed; secondly, the valve body blank is clamped on a valve body fixture; thirdly, the common center position of all machining portions of the valve body blank is selected, specifically, the cross center point of the X direction, the Y direction and the Z direction, namely, the center position of the valve body blank is selected; fourthly, one end of the valve body blank is finish-machinedtill the size required by the technological process is achieved; and fifthly, a micro rotating grinding head is installed on a lathe tool rest, and the sealing end face of a valve body casting is ground and polished through the micro rotating grinding head till the technological requirement is met. The valve body machining method has the advantages that the machining precision is high, small errors are generated, the working efficiency is high, the workpiece clamping frequency is low, the workpiece transferring frequency is low, the machining cost is low, and the rejection rate is low.