Digital physical hybrid simulation is an effective means of active distribution network simulation and analysis,and the interface algorithm is the key to ensuring the stability and accuracy of the system. Aiming at the problem that the existing interface algorithm cannot be applied to the hybrid simulation of active distribution network,an improved power interface algorithm based on virtual line compensation is proposed. Firstly,based on the analysis of the structure and stability conditions of the ideal transformer model (ITM) method,it is proposed to add a virtual line between the digital side and the physical side. Then,the stability of the system is compensated based on the virtual current on the line,and a range of values for the line impedance is given. At the same time,for the errors introduced by the inherent delay and stability compensation of the interface,it is proposed to compensate the phase difference between the two sides of the interface according to the virtual power flowing on the virtual line to ensure the accuracy. Finally,the proposed method is compared with the ITM method,damping impedance method and virtual impedance method by simulation and experiment. The results show that the proposed method is effective and superior in improving the stability and accuracy of the hybrid simulation system of active distribution network.