Abstract: The decision making in respect of a system usually means to decide relevant tactics based on a good grasp and analysis of the past records and the present condition about its background system. Therefore, the effect of the decision depends on not only the reasonableness of the tactics but also to a large extent on the dynamic stability of the background system. In this paper, concepts about the stability of a system and the reliability of decision making are proposed for a universal decision system based on a quantitative analysis. A set of simple stability measures for the decision making system and criteria for the reliability of the decision making are presented. The proposed measures and criteria can be used as the precondition of decision making and inspection basis for a universal system.