Abstract：The performance checking of the digital equipment in the smart grid need the three-phase power source with high quality. Now the common three-phase power source can output a single sinusoidal signal only. It can't satisfy these equipment’s performance checking. This paper develop a high precision standard three-phase programmable power source based on the power amplifier. The amplitude, phase and frequency of the output current and voltage can adjust independently, and it can output any waveform. These characteristics can satisfy the performance checking well. Because of the high dissipated power and poor stability of the power amplifier ,this paper proposes a overheating protection model based on several physical parameters, takes an effective output feedback control to improve its stability and accuracy.