Based　on　the　analysis　of　chloride　ion-induced　erosion　mechanism　of　reinforced　concrete,　a　multi-factor　model　of　the　chloride　ion　erosion　is　established.　In　this　model,　the　influences　of　water-cement　ratio,　humidity,　time,　temperature　and　chloride　ion　binding　capacity　of　concrete　were　taken　into　consideration,　and　the　mathematic　solution　of　the　new　model　is　given　out　by　considering　the　boundary　conditions.　The　new　model　was　verified　reliable　by　long-term　exposed　experiment　data　and　compared　with　the　traditional　model　of　the　Fick＇s　second　law.　The　results　showed　that　not　only　the　model　could　reflect　the　actual　chloride　ion　erosion,　but　also　the　prediction　effect　of　the　model　was　available,　especially　the　chloride　ion　concentration　of　different　periods　at　depth　more　than　25　mm.