As　a　part　of　software　non-functional　testing,　credibility　testing　is　an　important　means　to　ensure　the　quality　of　software.　However,　there　are　few　researches　on　the　credibility　testing　method　at　present.　In　this　paper,　a　new　method　of　generating　Credibility　test　cases　is　proposed　based　on　immune　algorithm.　By　mining　trustworthy　requirements　and　combining　with　immune　algorithm,　a　test　case　population　is　generated.　Based　on　the　result　of　test　case,　the　Application　Behavior　Declaration　is　improved　and　a　test　case　library　is　established.　The　conclusion　proves　that　the　trustworthy　test　cases　based　on　immune　algorithm　can　cover　the　credibility　requirements　and　improve　the　testing　efficiency.