The invention provides a press-fitting device for a piston pin. The press-fitting device comprises a bottom plate, a transmission shaft, a piston pin fixing shaft, a centering pressure head, the piston pin, a drive mechanism and a support rack, wherein the support rack is arranged at one end of the bottom plate and provided with a guide sleeve; one end of the transmission shaft is connected with the drive mechanism, and the other end of the transmission shaft penetrates the central hole of the guide sleeve to be connected with the mounting end of the piston pin fixing shaft in a threaded manner; the central hole is in slide fit with the transmission shaft; the mounting end is provided with blocking protrusion; the connecting end of the piston pin fixing shaft is connected with the centering pressure head in a threaded manner; the piston pin sleeves the piston pin fixing shaft, one end of the piston pin is abutted against the blocking protrusion, and the other end of the piston pin is abutted against the centering pressure head; the press-fitting end of the centering pressure head is of a conical structure; the transmission shaft has a first position and a second position. The press-fitting device has the advantages that the labor intensity of operators can be lowered effectively, and good assembling quality of the piston pin can be achieved.