Abstract: The PROMETHEE II method is extended to directly deal with the eigenspace that is expressed as interval numbers.The projection pursuit model of expert information pretreatment for group decision making is constructed in the perspective of optimal projection.Then,genetic algorithm is used to determine the weight.This method is particularly suitable for the occasions involving a number of alternative solutions.By a case study,this method is proved to be feasible and effective.It is ready for applications.

Key words: interval numbers, PROMETHEE II, weight determination, projection pursuit model