The invention discloses a live access method for a multi-terminal flexible direct current transmission system through a disconnecting switch, and belongs to methods for shutdown stations to have access to the multi-terminal flexible direct current transmission system. According to the method, other terminals have access to the multi-terminal flexible direct current transmission system operating normally through the direct current disconnecting switch. The method comprises the steps that the direct current voltage on the valve side of the disconnecting switch is controlled to reach the algebraic sum of the voltage on line side of a disconnecting link and the voltage decrement after a converter valve is switched off and meanwhile is controlled not to exceed the maximum value allowed by converter valve module; in the closing process of the disconnecting link, the converter valve is switched off at the computed time point, so the capacitor voltage of the converter valve decays to be the voltage on line side exactly at the moment when the disconnecting link is closed, and the situation that the disconnecting link cannot be closed due to the overlarge voltage difference of the two sides can be avoided; after the disconnecting link is closed, the end to be accessed is unlocked at the active and reactive power control mode. The method ensures that the converter valve is not impacted by switch-on current, solves the problem that the capacitor voltage of the module discharges too fast after the disconnecting link is switched off, and has the advantages of convenient operation and stable running.