<p>This study presents a comprehensive investigation into the dynamic behavior of particles with varying diameters transported by horizontal buoyant jets in linearly stratified fluids. An advanced modeling approach is developed that utilizes the realizable k-ε model based on Reynolds-averaged navier–stokes equations for buoyant jets mixing with stratified fluids, coupled with the discrete element method for particle tracking. The research employs a component transport model to simulate the intricate stratified environment, characterized by high-concentration saline and freshwater layers, with its accuracy validated using previous experimental data. A detailed numerical analysis of hydrodynamics and particle transport under different outflow and particle conditions reveals insights into the fluid-particle coupling mechanism and particle transport behaviors in horizontal buoyant jets. The results identified three primary modes of particle transport: settling during the upward stage, suspension diffusion within the neutral buoyancy layer, and settling during the horizontal stage. The findings reveal that particle size, density, and volume fraction profoundly influence these transport processes, and demonstrate that particles can substantially alter the jet’s flow structure, affecting the centerline trajectory, velocity decay, and the upper and lower half-widths. Furthermore, the study offers a novel perspective on the influence of particles on jet self-similarity and the statistical characteristics of particle sedimentation, advancing the understanding of the complex interaction between stratified fluid dynamics and particle-laden buoyant jets.</p>