Abstract: Aiming at the harmonic resonance phenomenon of three-phase LCL photovoltaic grid connected inverter from its high frequency resonant peak,a current double closed loop control strategy based on third-order LESO combined with second-order LADRC and quasi PR control is designed. It can better weaken the high frequency resonant peak and suppress the harmonic resonance phenomenon of photovoltaic system. By designing Lyapunov function,it is proved that the closed-loop system will eventually converge stably. The simulation results show that the double loop control strategy has superior robustness and practical application value.