How to describe and standardize the digital forensic requirement is an important part in digital forensic methodology.The paper propose the definition method of digital forensic requirement and an abstract model

named Environment Request Description (ERD).ERD definite three methods to describe digital forensic environment and requirement:Components

Environment Profile and Environment Target.ERD don't depend on a special digital forensic environment.Customer

developer and others depending on active usage could decide requirement.It will be useful to definite a forensic requirement in different and complex digital forensic environment.