Abstract: The SHA (Secure Hash Algorithm) family is a set of related cryptographic hash functions designed by the National Security Agency (NSA) and published by the National Institute of Standards Technology (NIST) .SHA-1 is one of them.The main applications of the SHA-1 function are met in the fields of communication integrity and signature authentication.Targeting the minimal area, an implementation of SHA-1 Algorithm in smart card chip is introduced.The Method introduced by this paper cost less area.And it can be referenced by the related design about hash algorithm implementation.