The electrothermal actuator designed in this article is used to play a delayed release role in the security mechanism of MEMS security systems, which requires periodic control signals to drive the centrifugal slider and other components of the security device through electric thermal force multi physics coupling in a complex mechanical working environment, enabling them to unlock and achieve reliable release of the security function. This article adopts the lumped parameter design method to establish a mathematical model of the electrothermal micro-actuator, and conducts theoretical analysis. Through finite element analysis and calculation, an electric thermal force coupling model of the micro actuator is established, and electrothermal energy conversion effect and the effects of V-beam parameters on the deformation and displacement of electrothermal micro-actuator are studied.