This study mainly investigates and researches the production of micro-torque limiters by using magnetic force and infrared optointerrupters therein including a permanent magnet, a magnet set, a grating disk, an infrared optointerrupter and a microprocessor, a torque-driven screw rod with the torque generated by the magnetic adsorption force. As the torque limiter is a clutch body, when the external resistance is greater than or equal to the magnetic torque, the rotation of screw rod will stop but start sliding simultaneously. When the screw rod stops rotating, the shutter detection disk also stops rotating. Correspondingly, the pulse signal output of infrared optointerrupters stops. Therefore, the motor of MCU stops by precisely determining whether the screw rod is stopped by external force with the function of torque limiters well exerted. As such, a product advantaged with streamlined sizes, long life expectancy, higher stability, low cost and handy control is reachable.