Abstract: Conventional strain-gauge method can not satisfy the measurement of the strain of mechanical component for its contacting pattern. Non-contact real-time on-line quantitative testing of the shear strain of the component twisted based on electromagnetic testing was put forward. AT89C52 based and angular strain testing system was designed. The system function, hardware structure and software design were also given. Simulation experiment showed that the system could provide reliable and accurate testing and was valuable for practical application.