The invention relates to the technical field of passenger car safety protection, in particular to a high-efficiency rollover preventing system for a passenger car. According to the high-efficiency rollover preventing system disclosed by the invention, the inclination angle of a car body is sensed by an inclination angle sensor arranged in the gravity position of the car body; in the travelling process of the passenger car, when the inclination angle of the car body exceeds a set critical angle, a command of opening baggage cabin doors is transmitted to a cabin door ejecting mechanism arranged between each baggage cabin door and the car body through a controller; and each baggage cabin door which touches the ground before the car body absorbs a part of impact energy in advance through a triangular structure consisting of a car body breast beam lower stand column, a cabin door stand column hinged to the car body breast beam lower stand column, and a folding pull rod of which the two ends are respectively hinged to the car body breast beam lower stand column and the cabin door stand column, so that the touchdown deformation of a car body structure is buffered and reduced, and the effect of protecting the living space of occupants is achieved. According to the high-efficiency rollover preventing system disclosed by the invention, a conventional car body structure can be better utilized, and the rollover preventing property of the passenger car is improved through an active manner.