With the development of cloud computing, outsourcing information to cloud server attracts scores of attentions. To ensure the safety and attain flexibly fine-grained file access management, attribute primarily based secret writing (ABE) was planned and utilized in cloud storage system. However, user revocation is that the primary issue in ABE schemes. During this article, we offer a ciphertext-policy attribute primarily based secret writing (CP-ABE) theme with economical user revocation for cloud storage system. The problem of user revocation will be resolved with efficiency by introducing the conception of user cluster. When any user leaves, the group manager will update users’ private keys except for those who have been revoked. Additionally, CPABE scheme has heavy computation cost, as it grows linearly with the complexity for the access structure. To reduce the computation cost, we outsource high computation load to cloud service providers without leaking file content and secret keys. Notably, our scheme can withstand collusion attack performed by revoked users cooperating with existing users. We prove the security of our scheme under the divisible computation Diffie-Hellman (DCDH) assumption. The result of our experiment shows computation cost for local devices is relatively low and can be constant. Our scheme is suitable for resource constrained devices.