To study the temperature characteristics of MEMS electrothermal actuators at micro-scale, taking into account the influence of air on the dynamic heat balance of the actuator, an electrical-thermal-fluid-solid coupled multi-field model based on air convective heat transfer is proposed. This model is based on the principles of energy conservation along with theories of gas convection and heat conduction. Finite element simulations are conducted to analyze the model. An experimental platform for temperature characterization of MEMS electrothermal actuator is established, and the experimental results of the temperature response of the actuator under constant voltage excitation are compared and analyzed against the simulation results from both the electric-thermal-fluid-solid coupling model and the traditional heat transfer model. The results indicate that compared with the model based on the constant convective heat transfer coefficient and empirical equations, the electric-thermal-fluid-solid coupling model achieves higher accuracy, with the steady-state temperature distribution error ranging between 0.8% and 7.6%. Additionally, the convective heat transfer coefficient varies across different surfaces of the actuator. Specifically it decreases then increases on the upper surface, increases steadily on the lower surface, and increases then decreases on the vertical walls. Despite these variations, the convective heat transfer coefficients on all three characteristic surfaces reach the steady-state almost simultaneously, coinciding with the actuator’s temperature reaching steady state. These findings, based on the uneven characteristics of air convective heat transfer, the obtained temperature characteristics of the electrothermal actuator provide a foundation for the application of MEMS electrothermal actuators in microelectromechanical systems.