The invention provides a constant power control method and system for a micro-source inverter applied to a microgrid. The method comprises the steps of collecting voltage and current signals outputtedby the inverter to a bus and carrying out Park conversion to obtain voltages vod and voq and currents iLd and iLq, subtracting iLd from a current value obtained by dividing an active reference valueby vod and inputting the difference into a current single-loop controller for adjustment to obtain an adjusted active current, dividing a reactive reference value by the voltage voq to obtain a current value and subtracting iLq from the current value and inputting the difference into the current single-loop controller for adjustment to obtain an adjusted reactive current, carrying out Park inversetransformation on the adjusted active current and reactive current to obtain a signal and carrying out signal modulation SPWM on the signal to obtain a control signal, and outputting the control signal to the inverter to control a switching tube and enabling the power outputted by the micropower inverter to be consistent with the power reference value. Thus, system voltage and frequency can be well kept to fluctuate with small deviation near rated values.