A columnar hydraulic tappet comprises a housing, in which a plunger is correspondingly mounted. A high-pressure chamber extends between a lower end surface of the plunger and a lower side of the housing. An outer ring groove is disposed on the outer diameter of the housing, an inner ring groove is disposed in the radial inner side of the housing, and housing oil feed holes are disposed between the inner ring groove and the outer ring groove. The lower end inside the housing is provided with a grinding wheel groove, an upper end wall of the inner ring groove of the housing is a first internal cylindrical wall, and a housing inner-wall between the lower end of the inner ring groove of the housing and the grinding wheel groove is a second internal cylindrical wall.