To improve the security and reliability of remote terminals under trusted cloud platform, an identity authentication model based on DAA optimization is proposed. By introducing a trusted third-party CA, the scheme issues a cross domain DAA certificate to the trusted platform that needs cross domain authentication. Then, privacy CA isolation measures are taken to improve the security of the platform, so that the authentication scheme can be used for identity authentication when ordinary users log in to the host equipped with TPM chip. Finally, the trusted computing platform environment is established, and the performance load distribution and total performance load of each entity in the DAA protocol in the unit of machine cycle can be acquired through experimental analysis. The results show that the scheme can take into account the requirements of anonymity, time cost and cross domain authentication in the trusted cloud computing platform, and it is a useful supplement and extension to the existing theories of web service security.