The invention provides a vehicle braking and steering combined system comprising an inflator (10), a motor (20), a steering oil pump (30), a controller (40) and a reduction box (100); the motor shaft of the motor (20) is connected with the input shaft of the reduction box; the first output shaft of the reduction box is connected with the steering oil pump; the second output shaft of the reduction box is connected with the inflator through an electromagnetic clutch (50); the controller is used for controlling the electromagnetic clutch to connector or disconnect. By using said structure, the reduction box has two output shafts, so motor power density can be improved, thus reducing motor volume, and reducing cost; in addition, two output shafts of the reduction box are respectively designed with different reduction ratios according to requirements of the inflator and the steering oil pump, i.e., the rotating speed of the motor, the steering oil pump and the inflator can be flexibly designed, and reduction ratios of the two output shafts can be coupled; the whole combined system is compact in structure, small in noises, and high in transmission efficiency and reliability.