With　the　continuous　expansion　of　software　scale,　its　internal　structure　is　becoming　more　and　more　complex,　and　its　application　environment　is　becoming　more　and　more　open.　These　factors　make　people　pay　more　attention　to　the　credibility　of　software.　Aiming　at　the　problem　of　low　accuracy　of　measurement　methods　in　software　credibility　evaluation,　this　paper　proposes　a　research　method　for　software　credibility　evaluation　based　on　fuzzy　mathematics　theory.　This　method　uses　fuzzy　sets　to　characterize　behavioral　declaration　and　actual　behavior,　and　then　respectively　give　the　credibility　measure　calculation　method　of　single　behavior　and　the　credibility　evaluation　calculation　method　of　software　as　a　whole　based　on　the　idea　of　＂words　and　deeds＂.　This　method　gives　the　evaluation　results　in　a　quantified　form,　which　improves　the　accuracy　of　the　evaluation　results　compared　with　the　previous　credibility　evaluation　methods　using　qualitative　analysis.　This　method　has　certain　practical　significance　in　the　credibility　evaluation　of　software,　and　provides　a　new　idea　for　measuring　the　credibility　of　software.