Proppants are widely employed in coalbed methane extraction. The use of proppant effectively mitigates the closure of hydro-fractures during production, thereby maintaining efficient gas flow pathways. The transport distance and accumulation morphology of proppants within hydro-fractures are critical factors influencing coalbed methane production; however, their quantitative and comprehensive evaluation remains insufficiently explored in coal reservoirs. In this study, a Box-Behnken design was adopted to establish a four-factor, four-level experimental framework for investigating the influence of multiple variables on dune parameters within secondary hydro-fractures through a coupled computational fluid dynamics-discrete element method approach. Response surface methodology and statistical significance testing were employed to quantify the effects of multiple parameters and to establish an empirical predictive model of proppant dune characteristics. The adequacy and significance of the proposed model were verified through analysis of variance. The results demonstrated that both the transport distance and accumulation morphology of proppant within hydro-fractures are jointly controlled by the coupled influence of multiple parameters. Four basic variables, including injection rate, proppant size, proppant density and sand carrying fluid viscosity, were selected, and their influences on sand dune parameters were ranked. The model predictions revealed that dune height may reach up to 79.7% of the hydro-fracture height, while the horizontal dune length can extend up to 15 times the hydro-fracture height. These findings elucidate the mechanisms governing proppant transport and deposition under diverse conditions, offering valuable insights and optimization strategies for proppant selection and injection parameter design in hydraulic fracturing in coalbed methane reservoirs.