The formal grey temporal security policy specification language (GTSL) which is designed by us is presented in this paper. The theory basis of GTSL is the theory of grey system and that of LOTOS, the language of temporal ordering specification. Due to the improvement and originality of techniques on the ability of integrity specification, the building and expression of the procedure of integrity verification, the testing of resonability on separation of duty, etc. , GTSL becomes practical specification languages for integrity security policy.