Abstract: In order to resolve the limit of classifying the vectors of linear inseparability using perceptrons with single layer，a method of sub-network analysis is developed in this paper，which is based on the perceptrons with one hidden layer.The sub-network analysis method is strict and accurate in construction of network but more complicated in preprocessing，which is suitable for classifying low dimensional vectors and will not produce misclassifying.The feasibility of this method is proved using three dimension vectors of linear inseparability.