The invention discloses a starting and stopping method for a static synchronous series compensator. The starting process includes the steps that a current converter is connected to a shunt transformer, and an incoming line switch of the shunt transformer is turned on to charge the current converter until direct-current voltage is stable; the incoming line switch of the shunt transformer is turned off, and the current converter is connected to a series transformer through a change-over switch; the current converter is unlocked, and the current of a by-pass switch of the series transformer is controlled to be approximate to zero; the by-pass switch of the series transformer is turned off, and the current converter enters a normal operation mode after a line is stable; when the static synchronous series compensator is stopped, the control mode of the current converter is switched first, the by-pass switch is turned on when the current is approximate to zero, then the current of the series transformer is controlled to gradually lower to zero, the series transformer exits, and then the current converter is locked. Overvoltage and overcurrent of the current converter when the series transformer exits can be effectively suppressed, current oscillation of the alternating-current line and the impact on the series transformer are reduced, and stable starting and stopping of the static synchronous series compensator are achieved.