The invention discloses a hard disk encryption method and device. The method comprises the steps that a domestic BIOS is used to perform identity authentication; during first starting, the domestic BIOS detects whether a secure storage card exists, when the secure storage card exists, the domestic BIOS reads a key from the secure storage card, and when the secure storage card does not exist, the domestic BIOS randomly generates a key; during non-first starting, the domestic BIOS acquires the key used in last starting; the domestic BIOS configures an encryption mode and a use algorithm and sends the key, the encryption mode and the use algorithm to a hard disk encryption chip; and the hard disk encryption chip acquires the key, the encryption mode and the use algorithm, and the hard disk encryption chip is used to perform hardware-level encryption/decryption on a hard disk. Through the hard disk encryption method and device, encryption speed can be increased, the key can be securely stored, and multiple encryption modes can be applied according to needs.