The invention relates to the technical field of motor machining, and discloses an adjustable positioning milling fixture with uniform clamping force. The milling fixture comprises a mounting table, the top of the mounting table is fixedly connected with a connecting block, four evenly distributed sliding holes are formed in the side wall of the connecting block, the four sliding holes communicate,sliding rods are in sliding connection to the inner walls of the four sliding holes, the ends, located in the connecting block, of the four sliding rods are fixedly connected with limiting blocks, limiting grooves are formed in the inner walls of the four sliding holes, the four limiting blocks are in sliding connection with the inner walls of the four limiting grooves, the ends, outside the connecting block, of the four sliding rods are fixedly connected with a first arc clamping plate, and a transmission box is fixedly connected to the bottom of the mounting table. According to the adjustable positioning milling fixture with uniform clamping force, a motor shell is sleeved with the position between a first clamping plate and a second clamping plate, the side wall stress area of the motor shell is increased, clamping force is transmitted by two opposite directions, and when the motor shell is clamped, the shell is not prone to deforming.