The invention discloses a replaceable express cabinet fixing device and its carrying vehicle. The fixing device includes an on-ground frame, a vehicle body, an express cabinet and parking lot devices.The on-ground frame is arranged at a diverging point of an express terminal, four on-ground frame lock sleeves are arranged on the on-ground frame, and each on-ground frame lock sleeve is internallyprovided with the parking lot device; each vehicle lock sleeve is provided with one parking lot device; four cabinet legs are arranged at the positions of four corners of the lower portion of the express cabinet, and the parking lot devices are used for locking the express cabinet tightly on the on-ground frame or the vehicle body through locking grooves; the express cabinet is a self-service express cabinet, expresses are placed in the express cabinet at the upstream of the diverging point of the terminal respectively, the express cabinet is tightly locked on the vehicle body through the parking lot devices, the express cabinet is moved from the vehicle body to the on-ground frame, and the parking lot devices are used for locking the express cabinet on the on-ground frame tightly. By arranging the replaceable express cabinet and its fixing device, express delivery is achieved, distribution links are reduced, and the work efficiency is improved. The parking lot devices are simple, practical, unique in principle and reasonable in structure.