The invention belongs to the technical field of medical instruments and particularly relates to a rotary expansion type interbody fusion cage. The rotary expansion type interbody fusion cage comprisesan upper fusion cage body, a lower fusion cage body, a transmission body and a transmission screw, a first circular groove is formed in one end face, close to the lower fusion cage body, of the fusion cage, a second circular groove is formed in one end face, close to the upper fusion cage body, of the fusion cage, the upper fusion cage body and the lower fusion cage body are hinged in the shape of 'X' through the transmission body, the first circular groove and the second circular groove are combined to form a cavity for accommodating the transmission body and the transmission screw, the lower fusion cage body is fixedly connected with the lower end of the transmission body, the upper fusion cage body is rotatably connected with the upper end of the transmission body, a threaded hole matched with the transmission screw is formed in the upper fusion cage body, and the free end of the transmission screw is clamped onto the transmission body. The rotary expansion type interbody fusion cage has the advantage that problems of great trauma, serious pain and long recovery time after implantation of the single fusion cage, or complicated operation, long operation time and insufficient stability after implantation of multiple fusion cages in the prior art are solved.