A reducer, an electric vehicle drive system with the reducer, and a control method for the electric vehicle drive system with the reducer comprises, in a reducer, a first countershaft is transmittingly connected to a first input shaft, a second countershaft is transmittingly connected to a second input shaft, and a centralized driving piece is transmittingly connected to a power input end of a differential apparatus. A first transmission assembly and a second transmission assembly are respectively configured to connect or disconnect power transmission between the first countershaft and the centralized driving piece and connect or disconnect transmission assembly power transmission between the second countershaft and the centralized driving piece. A first output shaft and a second output shaft are transmittingly connected to two power output ends of the differential apparatus respectively.