Abstract: As cloud storage technology attracts more and more attention, Security in cloud storage is now the biggest obstacle of cloud computing promotion. This paper proposes a new access control scheme in cloud. According to the characteristics of the users, they are classified as private users and public users. Use different ways to share the files and achieve the revocation of users. The sharing of files to public users adopts a multi-authority solution to reduce the burden of authorities and the risk of leaking information. Finally, analyze the security of the scheme and compare the efficiency of this scheme with those of other schemes. The results show that the proposed scheme can effectively solve the security problem in cloud storage.