The invention relates to the technical field of 
machining equipment, in particular to a special 
machine tool for sealing surface 
machining of hard sealing valve bodies. The 
machine tool comprises a base, and a valve 
body positioning and 
machining device arranged above the base; the valve 
body positioning and machining device consists of a valve 
body positioning device and a valve body machining device; the valve body machining device consists of adjustable valve body machining mechanisms distributed on the two sides of the valve body positioning device in a 
mirror image mode; and each adjustable valve body machining mechanism consists of an adjustable support mechanism, a valve body end surface machining mechanism and a 
tool bit module rotating 
radius adjusting mechanism. The 
machine tool is simple in structure, can stably position the valve bodies to be machined, and can synchronously machine two end surfaces of the valve bodies through the two valve body end surface machining mechanisms arranged in a 
mirror image mode to improve the machining efficiency; and in the 
machining process, through adjustment of the rotating 
radius of 
tool bit modules, the machining area of the 
tool bit modules is gradually enlarged, so that the machining of the whole surfaces of the valve bodies is finished, and the machining efficiency and the machining quality of the valve bodies are improved.