The invention provides an optimal decision method based on situation analysis and hierarchy analysis. The optimal decision method based on situation analysis and hierarchy analysis comprises the following steps of: first, establishing a multi-decision target index system on the basis of a situation analysis method; dividing decision targets into quantitative decision targets and non-quantitative decision targets; if the total quantitative decision targets play a dominant role in the total decision targets, determining a representative situation according to different states and constraint conditions of a decision variable; determining the weight of each quantitative target; calculating optimization values of different situations; sequencing the situations from small optimization value to big optimization value; selecting a plurality of former situations as initial optimal situations; and then decomposing the initial optimal situations into different hierarchy structures according to a hierarchy analysis method in a sequence of the total decision target, each sub decision target and the initial optimal situation; constructing a pairwise-compared weight judging matrix according to expert evaluation suggestions; calculating characteristic vector and matrix consistency of the judging matrix; figuring out a situation weight characteristic vector and a corresponding target weight characteristic vector; and finally, selecting an optimal situation. The method provided by the invention is simple and practical in technical realization.