A remote attestation mechanism, with high efficiency, flexibility and privacy protection based on Merkle hash tree is proposed in this paper. The problems of IMA (integrity measurement architecture) architecture are analyzed for a special target application scenario; followed by a detailed description of RAMT (remote attestation mechanism based on Merkle hash tree) architecture and its process of integrity measuring and verifying. The function and pseudo-code of command TPM_HashTree, which is a function enhancement to the existing TPM (trusted platform module), are presented for the newly proposed mechanism. The advantages of the new mechanism are analyzed and discussed.