Abstract: Since both the switch-off siding and fault train stop line should be set at the intermediate station of rail transit line under the operation mode of express and local trains, the engineering scale of sidings and the maintenance cost are inevitably increased. By studying relevant cases, the principle of switch-off siding serving as fault train stop line is proposed, which could increase the rescue speed, reduce the siding scale and rescue time, thus meet the operation requirements. The principle is applied on Guangzhou Line 14 and has achieved good operation results. The research results are adopted by Line 18, Line 21 and Line 22 in Guangzhou City at present.