Xiluodu Right Bank Power Station-Guangdong ±500 kV double-circuit high-voltage direct current（HVDC）transmission project sharing the same tower is the worlds first ever with the same converter station，which works both ways to adapt to operating independently，but also to adapt to the coordinated operation mode.Firstly，a hierarchical structure of the double-circuit HVDC control system is presented.Then according to the characteristics of the double-circuit control layer，a detailed research on the double-circuit HVDC power control function is put forward.A simulation model in PSCAD/EMTDC is built for this system for analysis of three typical operation modes.The feasibility and effectiveness of the coordinated control strategy is verified by the simulation results.