Abstract: In view of the inverter power coupling phenomenon,the root causes of inverter power coupling are analyzed theoretically,and the dynamic relative gain method in control theory is applied in the distributed power generation system,put forward a quantitative evaluation method of inverter power coupling degree in full frequency-domain,realized the correct pairing of the control parameters and the controlled parameters.Power decoupling control method based on diagonal matrix,improved the traditional droop control strategy,with voltage and current double closed-loop control and feedforward decoupling,realized the independent control of the inverter output active power and reactive power.Finally,the rationality of power coupling degree evaluation method based on dynamic relative gain was verified by a concrete example,and the feasibility of diagonal matrix power decoupling control method was verified by simulation experiment.This paper provides a theoretical reference and technical support for evaluation of power coupling and optimization for grid decoupling control.Finally,through concrete examples to verify the power coupling quantitative evaluation method based on dynamic relative gain.And the simulation experiment demonstrates the rationality of power decoupling control based on diagonal matrix method.