Because of the coupling and interaction of power delivery among the different ports in isolated three-port converter (TPC) and the small signal linear control model derived from specific steady state point, the parameters of control models will be varied with the change of operation state, this might result in degradation of control performance. In order to solve these problems, linear active disturbance rejection control (LADRC) method is employed for TPC. And an improved control model which is got by introducing virtual resistor is used to design LADRC controller for the TPC in this paper. The simulation results show that the three-port converter can achieve better performance balance in dynamic response and decoupling by using the proposed method.