Abstract: In order to study contact energy loss of AC miniature circuit breaker(AC-MCB) , simulation model of the 3-D contact energy consumption was established. The applied excitation was based on measured current data. At the connected state, simulation complete cycle and incomplete cycle energy consumption value was simulated and calculated, and power loss density color map in the specific time was given. The arcing was made into equivalent resistance of the contacts breaking process ,and the model of arc column was setted up , the power loss density color maps of arcing state was given in the specific time and energy loss values of contact breaking process was calculated. At last, the simulation results were analyzed, providing theoretical support and technical support of product structure and materials optimization.