The invention discloses a plug self-locking connector. The plug self-locking connector comprises a plug and a socket, wherein the socket is a square plate shell, a curved groove is formed in the outerwall of a cylindrical part, inserted with the plug, of the square plate shell, and an internal spline is arranged on the inner wall of the cylindrical part; the plug comprises a shaft-shaped spline shell and a cylindrical connecting nut, and the spline shell sleeves the connecting nut; an outer key groove is formed in the left end of the spline shell, and a protruding disc is further arranged inthe axial middle of the spline shell; a clamping nail is arranged in the left end of the connecting nut, a stepped hole is formed in the middle, and a key groove is formed from the stepped position tothe right end of the connecting nut; a disc of the spline shell is located on the right side of a middle stepped hole of the connecting nut. A locking washer, a corrugated spring and a clamping spring are sequentially arranged on the right side of the disc of the spline shell. A groove is formed in the right face of the spline shell disc, a protrusion corresponding to the groove in the spline shell disc face is arranged on the left end face of the locking washer, and a key is further arranged on the circumferential face of the locking washer. Self-locking of the internal structure of the plugcan be realized, and safe operation of high-precision equipment is facilitated.