The invention provides a pure electric wheelhub drive axle unit. The pure electric wheelhub drive axle unit is of a left-right symmetric structure, more uniform in a loading and bearing capacity, low in processing and manufacturing difficulty, adjustable in a total length of the driving axle, adaptable to various models of vehicles, reduces a development cost, improves a reduction ratio and improves an energy utilization rate. The pure electric wheelhub drive axle unit comprises the main axle body; the main axle body is of a left-right symmetric structure; motor arrangement grooves are arranged on two sides of the main axle body; positioning thread holes are arranged on end surfaces on two sides of the main axle body; the housings of the wheelhub decelerators are fixedly connected to the positioning thread holes on end surfaces of corresponding sides through bolts; a driving motor on the corresponding side is arranged inside the motor arrangement groove; a motor seat of the driving motor on the corresponding side is connected to an inner end surface of the housing of the wheelhub decelerator through a connection flange; and a brake assembly is fixed on the outer end surface of the housing of the wheelhub decelerator.