Abstract: In order to solve the problem of power circulation between parallel VSGs due to the different length of lines between parallel virtual synchronous generators and loads, a control strategy of parallel virtual synchronous generators based on adaptive virtual impedance is proposed in this paper. Firstly, the basic structure block diagram of two parallel virtual synchronous generators is established, and the power circulation is analyzed. In order to suppress the power circulation, an adaptive virtual impedance unit is designed. Secondly, the parameter tuning design of the control system of two parallel virtual synchronous generators is carried out. Finally, the system simulation model of parallel VSG are established without adaptive virtual impedance and with adaptive virtual impedance respectively, and the simulation example analysis is carried out under the condition that the rated capacity(1:1 and 2:1) of active power and reactive power of island operation and grid operation respectively. The simulation results show that the parallel VSG based on adaptive virtual impedance can well suppress the power circulation and achieve accurate power distribution.