The utility model relates to a steering system of a wheel-tread-adjustable vehicle. The steering system comprises a drive axle, an intersected drive axle, a main vehicle frame, a steering unit and steering link mechanisms. Center hinged mechanisms are formed between the drive axle and the main vehicle frame as well as between the intersected drive axle and the main vehicle frame. The drive axle and the intersected drive axle are installed on a vehicle frame main pin shaft which is a hollow shaft, a steering power arm main shaft penetrates through the vehicle frame main pin shaft and then is connected with a steering gear, and the steering unit and the steering link mechanisms are installed on the drive axle or the intersected drive axle. The steering link mechanisms and the steering unit are installed in a matched mode. Through the structure arrangement characteristic of the intersected drive axle and the characteristic of an adjustable wheel tread of the intersected drive axle, an Ackermann trapezoid steering mechanism is designed to be the independent steering unit, vehicle steering is achieved through the series of link mechanisms, the steering characteristic is changed through changing the structure parameters of the steering unit, and therefore the steering requirement under all wheel tread conditions is met.