This paper designs a film stress device which can apply stress to the film attached to a substrate, and describes the detailed structure of the film stress device, the strain of the central region of the film can be equal, the film strain calculation method and the derivation process are given, it can adjust the strain of the film by controlling the feed displacement of the device. The testing system is designed by combining the film stress device with the 3ω method, it can be used to study the effect of stress and thermal-stress coupling on the thermal conductivity of the film, the 3ω thermal conductivity method is analyzed.
