Percutaneous　coronary　intervention　with　stent　implantation　is　one　of　the　most　commonly　used　approaches　to　treat　coronary　artery　stenosis.　Stent　malapposition　(SM)　can　increase　the　incidence　of　stent　thrombosis,　but　the　quantitative　association　between　SM　distance　and　stent　thrombosis　is　poorly　clarified.　The　objective　of　this　study　is　to　determine　the　biomechanical　reaction　mechanisms　underlying　stent　thrombosis　induced　by　SM　and　to　quantify　the　effect　of　different　SM　severity　grades　on　thrombosis.　The　thrombus　simulation　was　performed　in　a　continuous　model　based　on　the　diffusion-convection　response　of　blood　substance　transport.　Simulated　models　included　well-apposed　stents　and　malapposed　stents　with　various　severities　where　the　detachment　distances　ranged　from　0　to　400　mu　m.　The　abnormal　shear　stress　induced　by　SM　was　considered　a　critical　contributor　affecting　stent　thrombosis,　which　was　dependent　on　changing　SM　distances　in　the　simulation.　The　results　illustrate　that　the　proportion　of　thrombus　volume　was　1.88%　at　a　SM　distance　of　75　mu　m　(mild),　3.46%　at　150　mu　m,　and　3.93%　at　400　mu　m　(severe),　but　that　a　slight　drop　(3.18%)　appeared　at　the　detachment　distance　of　225　mu　m　(intermediate).　The　results　indicate　that　when　the　SM　distance　was　less　than　150　mu　m,　the　thrombus　rose　notably　as　the　gap　distance　increased,　whereas　the　progression　of　thrombogenicity　weakened　when　it　exceeded　150　mu　m.　Therefore,　more　attention　should　be　paid　when　SM　is　present　at　a　gap　distance　of　150　mu　m.　Moreover,　when　the　SM　length　of　stents　are　the　same,　thrombus　tends　to　accumulate　downstream　towards　the　distal　end　of　the　stent　as　the　SM　distance　increases.