Inthispaper,wefocusonthevertex-fault-tolerantcyclesembeddingonenhancedhypercube,whichisanattractivevariantofhypercubeandisobtainedbyaddingsomecomplementaryedgesfromhypercube.LetFvbethesetoffaultyverticesinthen-dimensionalenhancedhypercubeQn,k（1≤k≤n-1）.When|Fv|=2,weshowedthatQn,k-Fvcontainsafault-freecycleofeveryevenlengthfrom4to2n-4wheren（n≥3）andfchavethesameparity;andcontainsafault-freecycleofeveryevenlengthfrom4to2n-4,simultaneously,containsacycleofeveryoddlengthfromn—fc+2to2n-3wheren（≥3）andfchavethedifferentparity.Furthermore,when|Fv|=fv≤n-2,weproofthatthereexiststhelongestfault-freecycle,whichisofevenlength2n-2fvwhethern（n>3）andfehavethesameparityornot;andthereexiststhelongestfault-freecycle,whichisofoddlength2n-2fv-1inQn,k—Fvwheren（≥3）andfchavethedifferentparity.
