Abstract: Hard disk drive is an important computers outer storage device, which is ra t her sensitive to random vibration circumstance, and is one of the weakest elemen ts in controlling the safety of computer system and information processing. Afte r analyzing the safety of the hard disk drive operating under random vibration c ircumstance, the general forms leading to operation failure of the hard disk dri ve are presented. According to the relationship between the head/disk relative d isplacement response on vibration excitation and read/write mode, the failure cr iterion of hard disk drive is provided. The result obtained provides a useful ex ploration on the safety analysis and estimation of the computer system under the condition of vibration.