The invention relates to a method for stopping series-side converters of multiple circuits of a unified power flow controller. The method comprises the steps of 1) decreasing output voltage of a series-side transformer of the series-side converter of any circuit to 0, and latching and controlling power flow of the current circuit; 2) carrying out an operation on the other circuits sequentially according to the step 1); 3) when the series-side converters of each circuit are latched and controlled at the power flow of the current circuit, sequentially closing bypass switches at primary sides of the series-side transformers; 4) sequentially transferring the power flow of each circuit to the bypass witch thereof after the bypass switches are closed; and 5) latching the series-side converter of each circuit so as to accomplish the series-side converter stopping process of the multiple circuits. According to the method provided by the invention, the power flow is stably lifted to the natural power flow before the converters are withdrawn, thereby effectively suppressing current surge when the bypass switches are closed, reducing power flow oscillation of an alternating current circuit, and realizing stable stopping of a double-circuit unified power flow controller.