The invention discloses an automatic alignment edge trimming machine for a pressure vessel end socket. The automatic alignment edge trimming machine for the pressure vessel end socket comprises an endsocket placement base, an alignment device and an edge trimming device; the alignment device and the edge trimming device are arranged on the outer edge of the end socket placement base; the alignment device is provided with rolling wheels capable of moving towards the center of the end socket placement base and infrared control switches; a circle concentric with the end socket placement base canbe formed at the center of the rolling wheels; and when all the infrared control switches make contact with an end socket, the rolling wheels synchronously moving towards the center of the end socketplacement base stop. The ellipticity error of more than 700 pieces of end sockets completed in the manner is controlled within +/-1.5 mm, and the profiling sample plate gap is controlled within 2 mm.