<p>The paper presents a numerical study of violent liquid sloshing on a two-dimensional rectangular tank of small dimensions by the Moving Particle Semi-implicit method. The numerical model considers a surface tension model to smoothly track the surface behavior, for this, pressure impact results were compared with and without a surface tension model. Also, the profiles during the run-up and run-down breaking waves on the sloshing process are compared with experimental results from the literature of similar scale. From these comparisons is highlighted the importance of the surface tension model on small dimensions on sloshing breaking waves, to an accurate simulation process, is showed by comparing the impact pressure with experimental literature results. Particle discretization for the numerical test considers two scales dimensions close to the experimental test from the literature, and two oscillation periods close to the natural resonant period of the fluid in the tank.</p>