Access control is an important mechanism in cloud computing. The Key Policy Attribute Based Encryption (KP-ABE) is an important method to implement the access control in cloud service. However, conventional user revocation scheme in KP-ABE costs huge computational overhead. In this paper, we focus on the important user revocation issue in KP-ABE. We introduce several control parameters, including version value, check value and user list. We combine KP-ABE with salt encryption for the implementation. We provide a novel user revocation scheme for KP-ABE to improve the user revocation issue, which can reduce the heavy computational overhead when user being revoked. The performance evaluation shows that the proposed user revocation scheme gives good performance with KP-ABE.