A rear sub-frame assembly for an electric vehicle body, wherein the rear sub-frame assembly comprises: a rear sub-frame main body, wherein the rear sub-frame main body is a bilateral symmetry structure, vehicle body connecting parts connected with the rear sub-frame main body on an upper portion of the rear sub-frame main body, and battery pack guard plate connecting parts connected with the rear sub-frame main body on a lower portion of the rear sub-frame main body are constructed on the rear sub-frame main body; and stabilizing rod mounting parts, upper control arm mounting parts and lower control arm mounting parts are further arranged on the rear sub-frame main body; and positioning supports, wherein the quantity of the positioning supports respectively arranged close to a left end and a right end of the rear sub-frame main body is two, and positioning parts matched with external positioning members to position the rear sub-frame main body are constructed on the two positioning supports respectively, wherein the rear sub-frame main body comprises a rear sub-frame body located in a middle part, and rear sub-frame cross beams and stabilizing rod mounting supports which are arranged on the two opposite sides of the rear sub-frame body respectively, and the rear sub-frame main body further comprises lower supports connecting disposed between the rear sub-frame cross beams on the two sides and the rear sub-frame body; and the positioning supports at the two ends are fixedly connected to the stabilizing rod mounting supports at the corresponding ends, characterised in that, the rear sub-frame body is provided with a rear sub-frame front plate and a rear sub-frame rear plate which are fixedly connected together in a lapped way, the rear sub-frame cross beams on the two sides are both fixedly connected with the rear sub-frame front plate in a lapped way, and the lower supports on the two sides are both fixedly connected between the rear sub-frame front plate and the rear sub-frame cross beams on the corresponding sides. a rear sub-frame main body, wherein the rear sub-frame main body is a bilateral symmetry structure, vehicle body connecting parts connected with the rear sub-frame main body on an upper portion of the rear sub-frame main body, and battery pack guard plate connecting parts connected with the rear sub-frame main body on a lower portion of the rear sub-frame main body are constructed on the rear sub-frame main body; and stabilizing rod mounting parts, upper control arm mounting parts and lower control arm mounting parts are further arranged on the rear sub-frame main body; and positioning supports, wherein the quantity of the positioning supports respectively arranged close to a left end and a right end of the rear sub-frame main body is two, and positioning parts matched with external positioning members to position the rear sub-frame main body are constructed on the two positioning supports respectively, wherein the rear sub-frame main body comprises a rear sub-frame body located in a middle part, and rear sub-frame cross beams and stabilizing rod mounting supports which are arranged on the two opposite sides of the rear sub-frame body respectively, and the rear sub-frame main body further comprises lower supports connecting disposed between the rear sub-frame cross beams on the two sides and the rear sub-frame body; and the positioning supports at the two ends are fixedly connected to the stabilizing rod mounting supports at the corresponding ends, characterised in that, the rear sub-frame body is provided with a rear sub-frame front plate and a rear sub-frame rear plate which are fixedly connected together in a lapped way, the rear sub-frame cross beams on the two sides are both fixedly connected with the rear sub-frame front plate in a lapped way, and the lower supports on the two sides are both fixedly connected between the rear sub-frame front plate and the rear sub-frame cross beams on the corresponding sides.