Abstract: When a partially-filled tanker truck is turning, the center of gravity of the liquid shifts, which negatively influences the roll stability of the tanker truck. An elliptical-shaped tanker truck with partially-filled liquid is taken as an example and its rollover mechanism in the course of turning is analyzed. With the liquid level change being approximately represented by a quasi-static process, the pressure on the internal wall of the tank is calculated to locate the pressure center and a quasi-static equivalent mechanical model for the roll stability of partially-filled tanker trucks under turning conditions is established. This model provides a theoretical basis for developing the rollover-warning system of tanker trucks. It is shown that the roll stability of the tank car is related to the cross-sectional shape of the tank body and the filling rate of the liquid, and the results can be used for improving the roll stability of the tank car.