The　rebar　corrosion　process　is　newly　partitioned　in　this　paper.　Based　on　the　concept　of　corrosion　parameters　and　principle　of　deformation　harmony,　the　relation　among　the　parameters　of　δ,　δ＇,　η0,　n,　PK　and　d0,　is　deduced,　and　which　are　respectively　represented　iron　rust　filling　zone,　increment　of　corrosion　rebar　diameter,　critical　rustiness　rate,　coefficient　of　rust　expansion,　opening　voids　within　concrete　and　steel　initial　diameter.　A　model　of　calculating　rust　filling　zone　relative　value　δ/d0　on　a　free　expansion　stage　is　built　up,　and　a　theoretical　model　of　calculating　main　pressure　stress　value　q*　due　to　rust　expansion　on　expansion　force　formation　stage　is　also　set　up　according　to　mass　conservation　law.　It　is　verified　to　be　reliable　and　suitable　for　the　calculation　models　by　indoor　test　result　analysis　and　also　proved　to　be　correct　by　the　corrosion　expansion　ANSYS　simulation　trial.　The　models　is　useful　for　forecasting　service　life　of　concrete.