The utility model discloses a gear backlash is adjusted structure, its axle on being positioned the box through location bearing, support bearing has the driven bevel gear wheel at this epaxial solid cover, and this driven bevel gear wheel is in between location bearing, the support bearing, and this driven bevel gear wheel with the initiative taper gear meshing on the box, wherein, the axle endwise slip set up in circle in location bearing, the support bearing, the location bearing with be provided with adjusting shim between the driven bevel gear wheel, and the epaxial cooperation of the location bearing other end has lock nut, and this lock nut will the axle is on and adjusting shim, driven bevel gear wheel locking positioning in circle in the location bearing. The utility model discloses a simple structure can eliminate the too big or undersize situation of gear backlash that manufacturing, assembly etc. Arouse, the assurance sideshake is in standard range, and the convenience is just adjusted to the location accuracy.