Abstract: By means of multi-terminal power electronic transformer (abbr. PET) the flexible power regulation path in AC/DC hybrid distribution network can be constructed for interaction and mutual aid of electric energy among multi-AC/DC hybrid distribution regions. A multi-terminal PET based day-ahead economic operation strategy for AC/DC hybrid power distribution network was proposed. Firstly, based on typical topology of AC/DC hybrid power distribution network, the flexible regulation and control capability of AC/DC hybrid power distribution network containing PET was analyzed. Secondly, according to physical constraint during the operational process of PET, the relation of power flowing of each terminal in multi-terminal PET was analyzed and an energy flowing model of the PET in AC/DC hybrid distribution network was built. Finally, taking the lowest operating cost of AC/DC hybrid distribution network as objective function and taking the system power balance, the power flow off-limit and the upper and lower limit constraints of equipment operation as the constraint conditions, a day-ahead economical operating model for AC/DC hybrid power distribution network was established and based on the CPLEX solver a method to solve the established model was put forward. Taking a demonstration project of an AC/DC hybrid power distribution network in a certain region in China for calculation example, a day-ahead economic operating model of this demonstration project was constructed and solved. The results of the calculation example show that using the proposed PET based economic operating strategy for AC/DC hybrid power distribution network the operating cost of the distribution system can be effectively reduced, and the accommodation level of renewable energy resource can be raised.