The invention discloses a machine reamer rotary device used for machining. The machine reamer rotary device comprises a base. The base is provided with guide shafts, a top base is arranged between the tops of the guide shafts, a hand wheel is arranged on the top base, and a guide pipe is arranged in the middle portion of the top base. A threaded column is inserted into the guide pipe, the upper end of the threaded column is connected with the hand wheel, and the lower end of the threaded column is a free end. The guide shafts are sleeved with a movable base. The lower end of the threaded column is arranged on the top of the movable base. One side of the lower portion of the front face of the movable base is provided with fixed bases. The upper portions of the fixed bases are provided with positioning blocks, positioning grooves are formed in the side positions of the positioning blocks, and an installation cavity is formed between the positioning blocks. Driven shafts are inserted into the positioning grooves, the inner ends of the driven shafts are arranged in the positioning grooves, and the outer ends of the driven shafts are provided with driven wheels. A drive motor is arranged on the back of the movable base, a drive shaft is arranged on the front portion of the drive motor, the outer circumferential face of the drive shaft is sleeved with a drive wheel, and the drive wheel and the driven wheels are connected through a drive belt. By means of the machine reamer rotary device used for machining, the efficiency of rotary operation of a reamer is greatly improved.