On August 8, 2009, the middle and south part of Taiwan was severely damaged by the Morakot typhoon. The Morakot typhoon is the worst storm to strike Taiwan in more than 50 years. Post traumatic stress disorder is a prevalent and prolonged anxiety disorder that may occur subsequent to a severe trauma. The major aim of this article was to introduce post traumatic stress disorder including its definition, diagnosis, related factors, and treatment. The contents of this article may provide a reference to increase typhoon victims' mental health for mental health nurses.