The utility model discloses an outer expanding anchor clamps of bearing ring, including the transition disc who is connected with the lathe main shaft, the chuck seat be connected with transition disc to and install holding ring and the jack catch on the chuck seat, the chuck seat is the tubulose, and chuck seat front side is the jack catch installation department of installation jack catch, lies in the fixed circular bead that the shaping of clamping jaw installation department rear side has the installation holding ring on the chuck seat, set up 6 along the axial equidistance on the anterior wall of chuck seat and exscinded the groove, the narrow conical surface in all shaping are extending outward in the chuck seat front end, outer expanding anchor clamps still include the well pull rod of being connected with the middle piston rod of lathe main shaft to and the front tension bar of being connected with well pull rod, the outer wall shaping of front tension bar rear portion have and the conical surface matched with taper surface of chuck seat. The new anchor clamps fast one time of back expanding spring perch in the aspect of the installation than the tradition outside that comes into operation, the one time that debug time is fast than before, and the jack catch external diameter can improve quite a few times in a lot of coping life -span than before.