This article focuses on the thermal design, improvement and implementation of a micro ammeter. Firstly, based on the heat flux density and its own characteristics, the idea of nature heat dissipation was proposed and modeled for simulation. The simulation results revealed that several heat-generating components were unable to reach the desired operating temperature, which could potentially affect the overall performance of the device. Therefore, improvement methods were proposed specifically addressing the unique structural features. Through simulation verification, environmental adaptability tests and reliability tests, the developed micro ammeter demonstrated stable performance and excellent results, sufficiently proving the effectiveness of the implemented heat dissipation methods.