The "stenter machine fabric entry guide system" is an automated control loop used for edge tracing of fabrics at the furnace exit of the stenter machine. The system is applied to a variety of materials, including cloth, plastic, paper, and Scotch tape. Especially for less reflective items, such as black cloth and black mesh, the system is able to accurately identify edge positions and achieve accurate edge alignment functions. The detector uses infrared light projection and reception to avoid the influence of other stray light, and contains digital signal processing to accurately determine the position. The driver uses a digital PWM servo drive system, which has high torque and high response characteristics, making the edge tracing process smoother.