Inspired　by　the　geomorphologic　phenomenon　of　step-pool　bed　configuration,　analogous　dissipation　structures　are　set　in　drainage　channels　to　mitigate　granular　flow　hazards.　The　sensible　design　of　artificial　step-pool　systems　remains　an　important　and　open　issue.　The　discrete　element　method　was　utilized　in　this　study　to　investigate　the　flow　characteristics　of　viscous　granular　flow　in　an　artificial　step-pool　system,　and　an　optimization　was　proposed.　First,　a　numerical　model　of　the　granular　flow–structure　interaction　was　given　and　validated.　The　influence　of　design　parameters　on　the　velocity　reduction　ratio　P　and　peak　impact　force　Fmax　was　then　investigated.　Finally,　a　new　step-pool　system　was　presented　and　evaluated.　The　results　reveal　that:　(1)　P　decreases　linearly　as　the　slope　i　increases.　The　relative　layout　spacing　ω　enhances　P　,　but　reduces　the　efficiency　of　velocity　control　per　unit　length　structure;　(2)　the　increase　in　ω　stabilizes　the　distribution　of　Fmax　on　2#　to　5#　baffles.　There　exists　a　“peak　effect”　of　the　average　peak　impact　force　Fa　with　the　variation　of　the　impact　angle　β　and　the　relative　baffle　height　ψ　(when　β　=　75°　or　ψ　=　0.27,　the　Fa　reaches　a　maximum);　(3)　the　optimized　structure　can　control　the　phenomenon　of　granular　jump　while　having　good　guiding　performance　and　more　stable　impact　characteristics.　The　energy　dissipation　rate　E　of　optimized　structure　reaches　91%,　an　increase　of　nearly　24%　over　the　original　structure.　©　2023,　The　Author(s),　under　exclusive　licence　to　Springer-Verlag　GmbH　Germany,　part　of　Springer　Nature.