Abstract: The problem of no power area existing in third rail current collection is analyzed from the perspective of vehicle traction system. The reliability of accurate detection and control method of no power area is analyzed in depth. The advantages and disadvantages of several current collecting methods used on maintenance lines are compared and analyzed. The technology of battery self\|traction is expounded. The control method of vehicle operation under car washing mode is described in detail. Through tests on Qingdao Metro Line 11, the feasibility of the selected method is verified.