The application provides a discharge method and device for a voltage sourced converter direct-current transmission line and a storage medium. The method comprises: unlocking a converter valve; generating an additional control signal by an additional controller and superimposing the additional control signal on a reference voltage output by a main controller of the voltage sourced converter direct-current transmission system, so that the converter valve generates a harmonic current in a three-phase bridge arm of a converter; and when a direct-current transmission line voltage is lower than a voltage setting or an average voltage of normal operating submodules in the converter bridge arm is lower than a submodule operating voltage setting, locking the converter.