Aiming at the problem of error protection of power supply circuit in the intelligent power meter, this paper presents ananalysis and optimization method of the intelligent power meter circuit based on power source temperature field simulation. First of all, build the power meter power circuit simulation model in Saber, to acquire the heating power of transformer. Then, the thermal simulation model of the energy meter machine is set up in Ansys Icepak, and the temperature field distribution of the energy meter is simulated and analyzed according to the heating power of the transformer and ambient temperature. Secondly, combined with the distribution of the loss of power of transformer, the protection characteristic of the energy meter is simulated and analyzed, and the probability of false protection is obtained. Finally, through the optimization of the iron loss of the energy meter transformer, the false protection probability of the power supply circuit is reduced and the protection characteristic is optimized.