The present invention discloses a method for protecting data in a hard disk, which is applied to the hard disk, such that if a computer executes boot codes of the hard disk and a hard disk identification code recorded by the hard disk is determined to be identical to a computer identification code stored in a computer, the hard disk can be read, which subsequently allows an operating system to be initialized, or else the content in a partition table area will be cleared and the hard disk cannot be read, thus the initialization of the operating system cannot be completed.