Cloud computing become more and more eye-catching these days. Each big company in IT areas hurries to win a chunk of meat which promises to be a whopping market in future. What make sense is advantages are inevitably accompanied by disadvantages. Subsequently, risks in cloud are also more and more compelling to people. This paper studies and researches on an array of experienced literature, presents an integrated risks table based on the risk key factors of cloud computing, and gives a comprehensive description for every risk.