The invention relates to a parking device, in particular to a lifting driving system adopting chain transmission, and solves the problem that a chain transmission lifting driving system of an existingstereoscopic parking garage is low in transmission power. The lifting driving system is characterized in that the lifting driving system comprises a main supporting frame, a host, two couplers, two groups of driving chain wheel components and two groups of driven chain wheel components, the host, the two couplers and the driving chain wheel components are arranged at one end of the main supporting frame, the driven chain wheel components are arranged at the other end of the main supporting frame, the host comprises a motor, a speed reducer and a first brake, the motor is connected with the speed reducer through the first brake, two output shafts of the speed reducer are connected with two driving chain wheel rotating shafts through the couplers, the number of driven chain wheels is halfof that of driving chain wheels, the outer driving chain wheel and the outer driven chain wheel form chain transmission, a tension wheel is arranged between the outer driving chain wheel and the outerdriven chain wheel, two ends of a first chain winding the driving chain wheel, the tension wheel and the driven chain wheel are connected with a counter weight and one end of an objective table, andtwo ends of a second chain only winding an inner driving chain wheel are connected with the counter weight and the other end of the objective table.