To　investigate　the　morphology　of　the　IEZ　under　natural　conditions,　a　large-scale　similar　ore　discharge　model　test　was　conducted.　Taking　the　first　phase　project　of　a　foreign　mine　as　the　context,　a　three-dimensional　similar　ore　discharge　model　test　was　designed.　The　motion　patterns　of　the　IEZ　were　analyzed　using　the　marked　particle　method.　Based　on　the　ore　drawing　kinematic　model,　along　with　an　improved　model　of　the　DP　relationship　for　the　ore　bulk　diffusion　coefficient　at　varying　IEZ　heights,　the　theoretical　morphological　parameters　and　characteristic　equations　of　the　IEZ　were　derived.　The　morphologies　of　the　IEZ　in　the　model　and　the　theoretical　calculation　results　were　compared,　and　the　morphological　behavior　of　the　IEZ　in　the　natural　caving　method　was　revealed.　The　results　are　shown　as　follows.　1)　The　overall　shape　of　the　IEZ　in　the　similarity　model　test　is　a　non-standard　ellipse　with　the　width　of　the　upper　part　larger　than　that　of　the　lower　part.　2)　The　relationship　between　the　ore　drawing　volume　and　the　height　of　the　IEZ　follows　a　power　function,　while　the　relationship　between　the　height　and　the　maximum　width　of　the　IEZ　follows　a　linear　function.　3)　Through　refinement　of　the　kinematic　model　and　the　selection　of　appropriate　parameters,　the　theoretically　predicted　morphology　of　IEZ　closely　aligns　with　the　experimentally　observed　morphology.　The　coefficient　of　determination(R²)　ranges　from　0.961　to　0.985,　thereby　validating　the　efficacy　of　the　improved　model.　4)　When　the　IEZ　height　reaches　200　m,　the　optimal　discharge　step　distance　is　determined　to　be　53.6　m,　with　the　predicted　optimal　ore　collapse　step　distance　ranging　from　35.7　m　to　41.23　m.　When　the　IEZ　height　reaches　300　m,　the　optimal　discharge　step　distance　increases　to　73.81　m.　©　2025,　Central　South　University.　All　rights　reserved.