Abstract: In order to avoid the loss caused by direct contact between testing equipment and yarn caused by traditional contact measuring method, a non-contact measuring method is proposed and a non-contact measuring system for yarn tension based on machine vision is designed. Use binocular cameras to detect the consumption speed of yarn ends, regulate the yarn's retraction and unwind speed, and maintaining stable yarn tension. The non-contact yarn tension measurement system based on machine vision, compared with the conventional tension control methods, the yarn tension change amplitude is only 25% of the original. This method has high accuracy and reliability, and can achieve active control of 3D braided yarn tension, with strong application potential.