Abstract: There are a large number of three-phase unbalanced loads in the distribution network, which makes it necessary to consider three-phase unbalanced voltage problem. Such problem also exists in microgrid. In order to solve this problem caused by three-phase unbalanced loads in microgrid, this paper proposes a novel three-phase voltage unbalanced compensation strategy for three-phase combined inverter based on Linear Active Disturbance Rejection Control (LADRC). Firstly, main reason leading to three-phase unbalanced voltage problem is analysed, and three-phase voltage unbalance degree is defined. According to the Kirchhoff laws, a dynamic mathematical model including known and unknown disturbances of microgrid and three-phase combined inverter is established to design Linear Extended State Observer (LESO). LESO is proposed to observe disturbance caused by three-phase unbalanced loads and the perturbations of internal parameters. Then the observed values are utilized as the control variables in feedforward compensation part. Finally, three-phase unbalanced voltage in three-phase combined inverter system can be adjusted by using a feedback approach based on Proportion-Derivative controller. In order to verify the effectiveness of the proposed compensation strategy, a simulation model is established on the MATLAB/SIMULINK platform. Then, several different three–phase unbalanced loads conditions are designed. The proposed LADRC method is compared with traditional PI double loop control method. The final experimental results verify that LADRC has a prior performance on reducing three-phase voltage unbalance degree, and getting lower total harmonic distortion (THD). Under different three–phase unbalanced loads conditions, the capacity of three-phase combined inverter carrying three-phase unbalanced loads is improved.