The loess hilly region is a specific and fragile zone of ecological environment.An evaluation of ecological security is particularly important to the agricultural development in the region.By using hierarchical analysis process,an indicator system is set up to assess the agricultural ecological security of typical county in the region.By taking Baota District in Yan'an City and Ansai County for an example,a mathematical model is used to calculate the index of agricultural ecological security in the two places and then the index is used to characterize agricultural ecological security status in the loess hilly region.Finally,in view of the ecological safety problems of this region,some recommendations are given.