Leg structure of office chair

The utility model provides a chair base structure of an office chair, which consists of an upper base seat, a lower base seat, and a roller. The upper base seat is assembled on the lower base seat, a hole and a threading sleeve are respectively arranged at the middle position of the upper base seat and the middle position of the lower base seat, and threaded by a supporting column, the roller is assembled at the bottom part of the lower base seat, the upper base seat and the lower base seat adopt the integrated forming and have a plurality of claw parts radiantly extending out of the middle position and, hooking pieces which are downwards and extendedly arranged are respectively arranged at the lower edges on the both sides of each claw part of the upper base seat, but clipping strips are convexly arranged at the upper ends on the end surfaces at the inner sides of the two side wall surfaces of the lower base seat, correspondingly hooked and clipped with the hooking pieces of the upper base seat, and the upper base seat and the lower base seat are assembled as a whole.