This paper emphasis that the positivist study of decision making in the part tend to prefer rational analysis to intuitive approach. Therefore, in addition to explanation of the characteristics of the units of analysis in detail puch as individual decision making, group decision making organizational decision making, this paper also discuss the decision rules and alternative methods of making decision. At last, the author present some points of the decision maker's mindsets, i.e. the problem of the proactive thinking, and the important value of multiplistic thinking.