Cloud computing provides great convenience for people's daily life,however,it also introduces huge security threats via related technology.Recently more and more vulnerabilities have been discovered for virtualization in IaaS of cloud platform,and it can be viewed as a difficult problem to discover DDoS and Escape vulnerabilities in virtualization mechanism.In this paper,some known bugs are analyzed for related platforms,target test case sets are extracted and extended,and randomized fuzzing test is designed and accomplished.In addition,an automatic prediction is proposed based on gray Markova model,via which the direction of fuzzing test can be supervised and adjusted in real time,and self-adapting fuzzing test can be achieved for virtualization platform.Finally,a prototype,called VirtualFuzz,is designed and accomplished in this paper.Experiment data demonstrates DDoS and Escape vulnerabilities can be discovered effectively in the new method.Out of 24 test cases acquired,18 known cases are evaluated and 6 unknown cases are discovered.Moreover,3 vulnerability authentications are obtained by CVE,while the optimized results for efficiency are emphasized via comparison between VirtualFuzz and other Fuzzing tools.