Nei Monggol autonomous region has a fragile and deterioration environment and is poor in self-regulating.An ecological enviroment precaution system is presented for this region in the paper based on a hierarchical model,which is established with the aid of the method of Analytic Hierarchy Process and consists of thirteen precaution indices for seven ecological construture and protective subregions of Nei Monggol.Through constituting judge matrixes,sorting model hierarchies,and testing consistency,crisis levels of the ecological environment are obtained for the seven subregions,and weights of the precaution factors and sorted orders of the crisis levels are estimated for each of them.Finally,detailed analysis is made in respect to the precaution results from the model.It can serve as a useful tool for protection and administration of Nei Monggol ecological environment.