The existing Ciphertext-Policy Attribute-Based Encryption(CP-ABE) relies on a single key generation center in cloud computing , which has the ability to decrypt all ciphertexts, therefore it must be fully trusted is the inherent defects. we put forward a new CP-ABE key issue protocol to solve the problem.The key generation center is responsible for the user identity authentication and attributes management，at the same time it must be with the other party such as cloud service provider through a security computation protocol to generate keys, neither of them has the ability to decrypt the ciphertexts . The scheme solves the security problems brought by the single key generation center , the end-user only needs once addition operation and greatly improved the computional efficiency . Finally the security proof of the scheme is given.