The invention discloses a flexible direct-current power regulation method for an island power supply. The flexible direct-current power regulation method includes the steps: (1) acquiring data of a flexible direct-current power transmission system; (2) judging whether the flexible direct-current power transmission system is controllable and adjustable or not; (3) selecting corresponding control modes according to different running modes when the flexible direct-current power transmission system is controllable and adjustable; (4) calculating regulation power according to the control modes selected in the step (3); (5) issuing regulation commands. The power of the flexible direct-current power transmission system is remotely regulated by a master power grid dispatching station, island power supply reliability is ensured, and the working intensity of power grid dispatchers is relieved.