Regarding　the　dynamic　trust　measurement　issues,　a　trust　measurement　model　for　a　software　system　written　in　C　language　by　combining　static　and　dynamic　measurement　is　designed.　To　gain　an　initial　way　to　abstract　the　behaviors　model,　the　software＇s　behavior　model　based　on　API　calls　is　constructed　firstly,　then　the　method　to　monitor　and　measure　the　real　behaviors　during　the　target　software　runtime　is　given.　The　experiment　results　show　that　the　model　can　reflect　software　behavior　better　and　enhance　the　system　security.　©　2012　IEEE.