Abstract: In the previous mining investment the investors only think about the characters of the orebodys.But in the practical mining investment decision,the circumstance of the market,the situation of the geography and economy,and the conditions of the companies are the unneglectable factors.Furthermaore,the three factors cannot be described with quantitative numbers.Using the method of fuzzy synthetic evaluation to decide whether the mining area can be mined or explored,this article evaluates every kind of ractors firstly,and then evaluates all the kinds synthetically.