A two-gear automatic transmission for a battery electric vehicle comprises an input shaft, an intermediate shaft, a first cylindrical gear pair, a second cylindrical gear pair, a third cylindrical gear pair, a first torque transfer device, a second torque transfer device and a differential assembly. The rotating central lines of the input shaft, the intermediate shaft and the differential assembly are mutually parallel. A driving motor, an automatic transmission and a driving bridge are integrated to form a whole, a transmission ratio range is widened, the performance requirement of the driving motor is remarkably reduced, the two-gear automatic transmission is simple and compact in structure, light in weight, stable in transmission and wide in transmission ratio range and has very high power transfer efficiency, energy consumption level is reduced, the power performance and economical efficiency of the whole vehicle are improved, and manufacturing cost is remarkably reduced.