The Xiala Formation can be divided into 3 parts which are grey and purple mid bedded bioclast limestone(first part)，grayish to dark grey bioclast and bioconstructed limestone(second part)，dark grey mid or thick bedded cherty micrite (third part) and their ages are Late Kungurian to Roadian，Wordian to Capitanian，Wuchiapingian respectively，according to lithostratigraphy and biostratigrphy based on reworking Zakang Mujiucuo Section of Xainza area，Tibet. Seven types of Microfacies and four types of facies — platform edge bioclast beach facies，platform edge bioherm，continental shelf，restricted platform — can been recognized from Xiala Formation using microfacies techonology. It is considered that the age of Xiala Formation is from Late Kungruian to Wuchiapingian successively and the sedimentary environments evolve from open carbonate platform to restricted platform. Thus，there is not exist stratigrahic gap and facies loss between Guadalupian and Lopingian in Xainza area.