In order to study the degree of liquid sloshing during the emergency braking of non-full load tank truck, the finite element method is used to simulate the liquid sloshing during the deceleration of tank truck. The influence of the number difference of the whole wave proof plate and the installation position of part of the wave proof plate with the same surface area on the liquid impact force is analyzed under the same filling ratio. The liquid pressure is loaded onto the wave proof plate as a load to study the stress change of the wave proof plate. The simulation results show that the impact force of liquid on the front head can be obviously reduced with the increase of the number of longitudinally-arranged full wave protection plates. Compared with the lower wave-proof plate with the same surface area, the upper wave-proof plate can not only reduce the impact force, but also increase the liquid impact force; The maximum pressure obtained by liquid sloshing is used as the load input of the wave-proof plate and it is found that the maximum stress occurs in the second wave-proof plate.