Particle dampers typically consist of freely moving granular materials contained within a structure mounted on a primary mass and induce structural vibration suppression through impact and friction. However, because granular materials do not move within the container when the vibration acceleration of the primary mass is low, particle dampers do not perform well. On the other hand, since liquid-filled particle dampers utilize liquid, their efficiency is far superior to that of solid-filled particle dampers at a low vibration acceleration. Although the damping effects have been described in many experimental and numerical studies, their investigations remain incomplete. Most previous research has primarily focused on the horizontal vibration characteristics of liquid-filled particle dampers. In this study, the damping efficiency of liquid-filled particle dampers in a vertically vibrating system under sinusoidal excitation was investigated experimentally and numerically. The motions of solid particles and the liquid were modeled using the discrete element method (DEM) and the moving particle semi-implicit (MPS) method, respectively. To verify the validity of the numerical method, an experimental apparatus that acts as an equivalent vertical single-degree-of-freedom system was used. The primary mass was excited sinusoidally via a spring using a shaker. The displacement of the primary mass was measured using a laser displacement sensor. The numerical results were compared with the experimental results to determine the relationship between the amplitude and frequency ratios. The results obtained indicate that MPS and DEM modeling can contribute to equipment design.