The invention discloses a drilling mechanism of a valve upper cap processing line. The drilling mechanism of the valve upper cap processing line comprises a drilling push-and-pull air cylinder connecting plate, a drilling push-and-pull air cylinder is mounted on the upper plane of the drilling push-and-pull air cylinder connecting plate through an air cylinder fixing seat. Two parallel drilling linear guide rails are mounted in the position, in front of the drilling push-and-pull air cylinder, of the drilling push-and-pull air cylinder connecting plate and are identical with the drill push-and-pull air cylinder in moving direction. A drilling push-and-pull plate is mounted on a slide block of the drilling linear guide rails. The side face of the drilling push-and-pull plate is fixed to a piston rod of the drilling push-and-pull air cylinder through a fixing seat. A drilling limiting seat is mounted in the position, located on the outer side of the drilling linear guide rails, of the drilling push-and-pull air cylinder connecting plate. In this way, the drilling mechanism of the valve upper cap processing line is simple in structure, easy and convenient to operate, and capable of fast completing drilling and hole milling.