Abstract: During shotcreting operations for underground mine support, shotcrete particles collide with the receiving surface at high velocity and break apart, forming dust emission sources. The diffusion of dust not only endangers workers’ health but also impairs the stable operation of equipment. To investigate the fragmentation mechanism and dust source strength of shotcrete particles in underground mines, the discrete element method (DEM) based on Altair EDEM was adopted in this study. Firstly, a micro-scale model of a single shotcrete particle impacting a rigid wall at high speed was established to simulate the entire fragmentation process and analyze the microscopic dynamic characteristics of particle breakage. Secondly, a macroscopic three-dimensional model integrating roadway and shotcrete particle groups was built to simulate shotcreting at different spray angles. The motion trajectories and mass distribution of dust generated by fragmentation were tracked inside the roadway. Measuring points were arranged near the receiving surface and along the roadway to calculate dust mass and source strength at each point, so as to clarify the influence of spray angle on the spatial mass distribution and source strength of fugitive dust in roadways. The results show that the fragmentation of shotcrete particles undergoes three microscopic stages: initial deformation and fracture, disintegration upon impact and rebound, and splashing driven by residual kinetic energy. Spray angle is a key parameter for regulating dust source strength and spatial mass distribution. The respirable dust emission at the vertical spraying (spray angle of 90°) and horizontal spraying (spray angle of 70°) decreases by 57.1%-89.1% compared with other spray angles. The dust source strength presents a gradient distribution of high values in near areas and low values in distant areas. The variation trend of dust source strength with spray angle is consistent with that of total dust mass. A higher proportion of respirable dust corresponds to a faster growth rate of dust source strength. This study adopts coupled micro-macro simulation to reveal the core mechanisms of dust generation and diffusion during shotcreting, and quantitatively determines the optimal spray angles and their dust suppression effect.