Abstract: The optimal utilization of residual coal resources following underground coal mining is a critical issue in enhancing resource exploitation efficiency. The optimal utilisation of residual coal resources following underground coal mining is a critical issue in enhancing resource utilisation efficiency. This paper highlights the key advantages of using the PFC (Particle Flow Code) numerical simulation technique to provide an accurate model of coal−rock mass deformation and failure. By investigating and organising research on this simulation technology in the context of the coal seam mining process, the prediction of surrounding rock and roof deformation and failure, and the evolution of multi−field coupling reservoir properties, this paper aims to discuss the progress of the particle flow simulation application in the utilization of residual coal. Based on the discrete element characteristics of particle flow simulation, this paper presents two applications of particle flow simulation in residual coal utilization: (1) particle flow simulation can guide the selection and optimization of appropriate process parameters in residual coal mining and recovery and evaluate the impact of different mining methods on the stability of the surrounding rock and surface subsidence. The simulation can also be used to optimize the roof caving recovery scheme. (2) In the process of in−situ conversion and utilization of residual coal, particle flow simulation recreates the fracturing of the coal rock mass and the formation of gasification cavities under multi−field coupling conditions. It also provides a quantitative analysis of the changes in reservoir porosity and permeability under gasification and pyrolysis processes. Particle flow simulation is a valuable tool for enhancing the recovery and utilization capacity of residual coal and designing in−situ coal conversion projects.