Abstract: Abstract: In order to study the effects of liquid sloshing on the driving stability of a tank truck, in the light of the problem of the horizontal fluid sloshing in the tank body, the governing equations of the transverse liquid sloshing within tank body are established by potential theory. The Galerkin method was used to establish a discrete forced sloshing equation of the fluids in the tank, and the force of the liquid forced sloshing on the tank was solved. According to the equivalence principle, an equivalent mechanical model of liquid forced sloshing was established. Based on the additional torque produced by the lateral movement of the liquid mass center and the force of the liquid sloshing pressure against the tank, combined with the rigid model of the semi-trailer, the mathematical model of the liquid tank semi-trailer was established. For liquid and solid cargoes, the impact of the liquid sloshing on the driving parameters and instability forms of the liquid tank semi-trailer was simulated comparatively by the two conditions of the step steering and double-shift line. Simulation results shows that: in the step steering, the liquid sloshing has the greater impact on the roll angle and reduces the threshold of the rollover speed of the vehicle, but has a smaller impact on the other operating parameters. In the double shift line condition, the liquid sloshing intensifies the fluctuations of the lateral acceleration and hinged angle, and makes the vehicle transverse shimmy significantly. When near the working-fluid filling rate of 1.2, with the increasing of the speed, the pendulum vibration instability occurred initially, and then the rollover occurred. When closing to the full charging rate, with the increase of speed, vehicles will rollover directly. The paper provides reference for stability control research and safety driving of semi-trailer liquid tank.