Whether　coexisting　microplastics　(MPs)　affect　the　ecological　and　health　risks　of　cadmium　(Cd)　in　soils　is　a　cutting-edge　scientific　issue.　In　this　study,　four　typical　Chinese　soils　were　prepared　as　artificially　Cd-contaminated　soils　with/without　aged　polystyrene　(PS).　TCLP　and　in　vitro　PBET　model　were　used　to　determine　the　leachability　(ecological　risk)　and　oral　bioaccessibility　(human　health　risk)　of　soil　Cd.　The　mechanisms　by　which　MPs　influence　soil　Cd　were　discussed　from　direct　and　indirect　perspectives.　Results　showed　that　there　was　no　significant　difference　in　the　leachability　of　soil　Cd　with/without　aged　PS.　Additionally,　aged　PS　led　to　a　significant　decrease　in　the　bioaccessibility　of　soil　Cd　in　gastric　phase,　but　not　in　small　intestinal　phase.　The　increase　in　surface　roughness　and　the　new　characteristic　peaks　(e.g.,　Si-O-Si)　of　aged　PS　directly　accounted　for　the　change　in　Cd　bioaccessibility.　The　change　in　organic　matter　content　indirectly　accounted　for　the　exceptional　increase　in　Cd　bioaccessibility　of　black　soil　with　aged　PS　in　small　intestinal　phase.　Furthermore,　the　changes　in　cation　exchange　capacity　and　Cd　mobility　factor　caused　by　aged　PS　explained　the　change　in　Cd　leachability.　These　results　contribute　to　a　deeper　understanding　about　environmental　and　public　health　in　complicated　emerging　scenarios.　©　2024　Elsevier　B.V.