The utility model discloses a post-processing system integrated device which comprises a fixed support, a deceleration control unit (DCU), an air compression part, a urea pump, a relay box and a heating water valve. The DCU, the air compression part, the urea pump, the relay box and the heating water valve are fixedly connected with the fixed support. The fixed support comprises a base plate and fixing plates of the DCU, the air compression part, the urea pump and a label board. One end of a fixing plate of the air compression part is connected with a fixing plate of the DCU, the relay box, the heating water valve and the fixing plates are located on the opposite sides of the base plate, the fixing plate of the DCU and the fixing plate of the label board are located on the opposite sides of the base plate, U-shaped space is formed among the fixing plates, the DCU, the air compression part and the label board are located on the outer portion of the U-shaped space, and the urea pump penetrates the U-shaped space. The post-processing system integrated device has the advantages of being compact in connection structure, simplifying an installation process, improving working efficiency and further improving urea box capacity.