Abstract：The advantages with the use of the pattern recognition method to study the characteristic of the reservoir and dam groundwater seepage field are described briefly. According to the theory of fuzzy selection，the mixing ratio model is built. It presents the criteria to classify the water samples quantitatively through application based on the difference and relation among various samples，and offers the precondition in order to describe target pattern. According to the basic concept of pattern recognition and combining with the theory of multifunction and BP network，the multi-factor increment model is established. The target value of each pattern is unique. The model can filter and harmonize valuable information，and deduce the target model value by analyzing the increment between known and unknown variables. An instance of Longyangxia dam groundwater seepage field is provided. It shows that there are so many merits about the pattern recognition method within the research domain of groundwater seepage field characteristic and supply relationship，such as the interfere from subjective or impersonality is avoidable，it is easy to program，the process and results are clear.
