In the production process of yarn, tensile performance testing is an important process. In order to improve the grade and quality of finished products, the microcomputer measurement and control system of yarn tensile testing machine was developed. The system is composed of host, tensile measurement sensor, extension measurement sensor, automatic return positioning unit and upper computer, the host adopts 77E58 single-chip microcomputer, adopts high-precision A/D converter, and the rate is up to 100 times/s; Maximum load 1 kN; Minimum value 0.01 N; Accuracy class: 0.1 grade; Test speed range 0.005~500 mm/min; Displacement measurement accuracy: within ±0.1% of the indicated value; Displacement measurement resolution: 0.01 mm. The test shows that the system has high detection accuracy and fast data processing speed, and can be used with various tensile testing machines used in building materials, textiles, metal products, paper products and other industries, and has a good promotion and application prospect.