The invention discloses a heavy-duty-car rollover-preventing system, and relates to the technical field of heavy-duty-car safety design. The heavy-duty-car rollover-preventing system comprises a gyroscope, distance sensors, a controller, a control panel and hydraulic pressure assemblies. The gyroscope, the distance sensors, the control panel and the hydraulic pressure assemblies are connected with the controller, the gyroscope is installed at the bottom of a middle cross beam of an automobile frame, and the distance sensors are installed at the bottoms of the two sides of the automobile frame; and the hydraulic pressure assemblies are installed on the two sides of the automobile frame, and the control panel is installed in an automobile control room. In the working process, the gyroscope detects the side-lurching state of the automobile frame, the distance sensors detect the distance between the automobile frame and the road surface, and the gyroscope and the distance sensors transfer collected data to the controller; the controller analyzes the data comprehensively, and the side-lurching degree of an automobile is judged and displayed on the control panel; and a driver controls the motion of the hydraulic pressure assemblies through the control panel, balance of the automobile is kept, and the heavy-duty-car rollover-preventing effect is achieved through the technological means.