Abstract: The grid security is an important component, and it directly affects the development of the grid and the practical application of grid system software. In order to fully describe the information flow based on grid environment, a new security information flow model based on grid environment was given, in which the safety class was divided and the information flow policy was defined by using the organisation security classifications, classifications, and integrity grade of the object. In this article,the subject and the object were extended,and the concepts of the decomposition of the subject and object,and of organisation security classification were defined. hhe strict mathematics verification shows that this new information flow model satisfies the character of finite lattice and least upper bound operator of the Denning's information flow model,it is reasonable and safe. It is an extension of information flow model contrast to BLP model's and Biba model's, but also the expansion of security information flow model based on the general network environment, and there has some positive significance for the study grid security.

Key words: Grid security,BLP model, Biba model, Information flow model