The utility model provides a back suspension is with swing arm down, back suspension and automobile, wherein, back suspension includes with lower swing arm: lower swing arm body, down swing arm body one end is used for connecting with the sub vehicle frame, the other end be used for with the wheel leg joint, the swing arm body is used for being equipped with two at least first connecting pieces with the one end of sub vehicle frame connection down, the swing arm body is used for being equipped with two at least second connecting pieces with the one end of wheel leg joint down, still be equipped with shock absorber mount pad and elastic element mount pad down on the swing arm body. The utility model discloses do not set up vertical arm of transmission longitudinal force, lower swing arm body can play the effect of transmission longitudinal force, leaves the longitudinal arrangement space that the battery is more for, is favorable to improving the continuation of the journey mileage of vehicle, when the shock absorber breaks down, need not to dismantle coil spring again and maintain for it is more convenient to maintain.