Abstract: By a brief introduction to the fundamental principle and construction procedure of Grey Model GM(1,1),three examples are listed about applying this model to deep level quantitative metallogenic prognosis of gold deposits After a comprehensive comparison and analysis of the prospecting results,it is concluded that the variation degree of ore body itself,and monotonous function feature of the model are main factors that influence the prognostic precision The study on the variation degree and regularity of ore body is the premise and base for effective prognosis with GM(1,1) model.