Full disk encryption is good choice to solve the problem of information leakage. in this paper, a full disk encryption based on virual machine is proposed for computers without TPM. the program to decypt the operating system is stored in a USB device which is more secure than in hard disk together will confidential information. a smartcard is used for enhancing security and the key recovery scheme. the experiments, security analysis and comparison demonstrate the efficiency, security and advantage of the proposed scheme.