Abstract: Based on the self-consistent RBUU transport theory, the isospin-dependent in-medium \rmN \Delta \rightarrow \rmN \Delta cross section is investigated. It is found that the isospin effect has a relatively obvious influence on the effective mass of baryons and the total \rmN \Delta elastic cross section in different density regions. With the increase of baryon density, the effective mass splitting between different isospin states of baryons increases gradually. Under the joint effect of density-dependent baryon effective mass splitting, coupling constant, as well as Born terms such as \sigma-\delta, \sigma-\rho, \omega-\delta, \omega-\rho, the elastic cross-sections of sub-channels with different isospin states exhibit different density-dependent behaviors. The total cross-section has an obvious reduction effect of medium in the low-energy region, and the medium effect is weakened in the high-energy region.