A battery necking machine comprises a rack, a rotation shaft and a driving assembly, wherein the rotation shaft is arranged on the rack, a press rod lifting cam, a press rod rotation wheel, a rotation disc, a top rod rotation wheel and a top rod lifting lower cam are sleeved on the rotation shaft, a top rod lifting guide surface is arranged between the rotation shaft and the top rod lifting lower cam, the press rod lifting cam, the top rod lifting guide surface and the top rod lifting lower cam are fixed with the rack, the press rod rotation wheel, the rotation disc and the top rod rotation wheel are fixed with the rotation shaft and rotate with the rotation shaft, the press rod assembly is circumferentially arranged on the press rod rotation wheel, rotates in the same direction of the press rod rotation wheel and upwards and downwards moves relative to the press rod rotation wheel, a top rod assembly is circumferentially arranged on the top rod rotation wheel, rotates in the same direction of the press rod rotation wheel and upwards and downwards moves relative to the top rod rotation wheel, station holes are formed in the rotation disc and are arranged between the press rod assembly and the top rod assembly, the press rod lifting cam is connected with the press rod assembly so as to guide the press rod assembly to upwards and downwards move, and the top rod assembly is guided to upwards and downwards move between the top rod lifting guide surface and the top rod lifting low cam. The top rod assembly is used for positioning a lower end of a battery, the press rod assembly is used for stamping a shoulder part of the battery so as to reduce shoulder height, and the burst pressure of the battery is increased.