Death obsession is a type of death-themed compulsive thinking， the assessment tool of which is the Death Obsession Scale（ DOS）. The impact factors of death obsession are divided into environmental factors and individual factors. Environmental factors include the different regions and the stability of local political environments. Individual factors can be divided into whether individuals have religious beliefs， whether individuals are pessimistic or optimistic and gender factors. This paper reviews the concept， assessment tool and influencing factors of death obsession.