The invention provides a barrier-free self-propelled cart assembly which is provided with horizontal gravity center shifting devices arranged on the two sides of a chassis. Drive units of the horizontal gravity center shifting devices are arranged on the chassis. At least one longitudinal horizontal-moving guide device is arranged on the chassis in the advancing direction of the moving device. Sliding bases matched with the horizontal-moving guide devices are arranged on the power portion of a connecting rack. A sector gear is fixed to one sliding base. A drive motor is fixed to the lower portion of the connecting rack. A motor drive shaft is connected with a gravity center moving transmission gear engaged with the sector gear, and further connected with a horizontal-moving transfer gear box in a transmission mode. The power output shaft of the transfer gear box is axially arranged on the connecting rack in a pivoted mode. Drive gears engaged with racks fixed to a chassis correspondingly are arranged on the power output shaft. The barrier-free self-propelled cart assembly is applied to large-slope road conditions, the gravity center and horizontal balance can be guaranteed, and adverse influence on passengers or cargoes is avoided.