The invention discloses a rear drive axle assembly. The rear drive axle assembly comprises an axle casing which is in a girder structure, two wheel hubs, a main reducing gear and differential mechanism assembly, a braking assembly, a hub reduction gear, a forced differential lock and a parking brake, wherein the forced differential lock comprises a sliding meshing sleeve, a differential mechanism lockpin, a piston, a selector rod, a back-moving spring and a shifting fork, the shifting fork is connected fixedly with a shifting fork shaft, the back-moving spring is arranged between the shifting fork and the shifting fork shaft, a groove which is matched with the shifting fork is arranged on the sliding meshing sleeve, grooves which are matched with the differential mechanism lockpin are arranged on the sliding meshing sleeve and a driving shaft gear of the main reducing gear and differential mechanism assembly correspondingly, the parking brake comprises a brake body and a brake disk, the brake body is arranged on a main reducing gear casing of the main reducing gear and differential mechanism assembly, the brake disk is arranged on a main tooth flange, and a plane and an installation hole, which are connected with the machine base plate, are arranged on the axle casing. The rear drive axle assembly has the advantages of being good in parking and heat radiation performance, large in bearing capacity, simple in structure and convenient to process and produce.