Abstract: Nowadays,the research for the realization of IDSS has already became the focus of various subjects.Especially,with the development of the artificial intelligence,there are many new theories and methods used in the realization of IDSS.The writers explore hereinafter the intellectual expression in IDSS,discuss the application of property in the intellectual expression system and the nature and function of the intellectual expression system of decision form and the useful character of the information which is analyzed and dealt with numerous information and based on rough set theory.Through analysis and speculation,the minimun decision rules come into being.