The invention discloses an automatic chain shearing machine for closed-end zippers. The automatic chain shearing machine comprises a shearing platform, a traction device and a shearing device, wherein a zipper channel is arranged on the shearing platform, the traction device and the shearing device are coaxially arranged on the zipper channel, and the shearing device is positioned at the rear side of the traction device. The automatic chain shearing machine further comprises an induction device, the induction device comprises a cantilever fixed on the front end surface of a positioning frame, a conductive rod is arranged below the cantilever, the middle of the conductive rod is pivoted to the cantilever, a contact column is fixed on the bottom surface of the rear end of the conductive rod, the front end of the conductive rod is connected with the cantilever through a return spring, and a proximity switch is arranged on the cantilever, is located between the front end of the conductive rod and the pivot point, is switched on or switched off on the basis of the distance to the conductive rod and is used for controlling an impact cylinder to act. According to the automatic chain shearing machine, by arranging the traction device and the shearing device, long zipper tapes can be automatically fed and cut, and the cutting efficiency of the closed-end zippers is improved.