To study the effect of perforation rate of vertical baffle on the liquid sloshing characteristics, a six-degree-of-freedom motion simulation platform was used to conduct a series of sloshing lests in a rectangular tank with the bafles of different perforation rate. The external excitation frequency values are 0. 8~1. 2 time the first-order natural frequency of the tank. The results show that the perforated baffle with a porosity of 0. 1 is better than an unperforated bafle in reducing the maximum sloshing wave height and the maximum impact pressure at some places under different external excitation frequencies. The damping effect on sloshing of the perforated baffle increases with the decrease of the perforation rate. When the external excitation frequeney is the natural frequeney, the main frequency component of the sloshing wave height is the same as the external excitation frequency. When the external excitation frequency is not the natural frequency, the main frequeney of the sloshing wave height also has a frequency multiplication, and the frequency multiplication gradually disappears with the increase of the perforation rate.