Abstract: In order to reduce the failure probability of ATO (Automatic Train Operation) control system of urban rail transit train, traction and braking control circuits of Hefei Metro Line 1 and Line 2 in ATO mode are designed with redundancy on both vehicle sides and signaling sides. Through indepth analysis, it is found that the control circuit redundancy design has some defects in the interface, which leads to doubled fault probability of traction and braking control circuits, shortening the service life of AMTDR (traction instruction relay) and AMBDR (braking instruction relay). To solve this issue, two technical schemes to optimize the power generation logic of AMTDR and AMBDR are proposed.