The invention discloses a piston cooling nozzle and a piston cooling nozzle and piston centring checking method, and belongs to the technical field of engines. The piston cooling nozzle comprises a valve base with a first axial cavity, a main sliding valve and a main reset element are arranged in the valve base, one end of the first axial cavity is provided with a first oil inlet, and the side wall of the valve base is provided with a first oil outlet. The end, away from the first oil inlet, of the main sliding valve is provided with a second axial cavity. An auxiliary sliding valve and an auxiliary reset element are arranged in the second axial cavity. The end, away from the first oil inlet, of the main sliding valve is fixedly connected with one end of a hollow connector, the other end of the hollow connector penetrates out of the valve base, and the side wall of the main sliding valve is provided with a second oil outlet. The piston cooling nozzle is adopted in the piston cooling nozzle and piston centring checking method. Accordingly, engine oil external connection can be achieved, the piston cooling nozzle and piston centring situation can be checked, and faults related to insufficient piston cooling due to centring differences are reduced.