It proves challenging to analyze the particle dynamics experimentally, particularly in a multiphase microreactor. A numerical model based on volume of fluid (VOF) coupled with discrete element method (DEM) is developed to investigate the particle dynamics in the liquid slugs of a gas-liquid-solid Taylor flow microreactor. The detailed implementation of the coupling and numerical schemes is presented. The coupling scheme of VOF-DEM allows for the fully resolved fluid flow on a mesh with the resolution much finer than the particle size, while accurately capturing the complex fluid-particle interactions. Good agreements were achieved when comparing the liquid film thickness and bubble rising velocity predicted by the VOF-DEM model against those calculated using existing empirical and analytical correlations. The predicted bubble shapes and particle flow patterns were also in line with the findings reported in the literature. Further analysis of the particle distribution indicated that particles preferentially concentrated in different regions under different operating conditions. Despite the complexity of the multiphase flow system, the particle trajectory generally exhibited the steady zigzag pattern and was highly controllable.