Abstract: In order to further research the properties of neural networks when their BP algorithm is used in mode classification，this paper proposes four ways of offering training samples to multi一layer neural networks, and makes a comparison between them. The results show that the better ways are random input mode and partial input mode，therefore the input mod-
es of traing samples have direct influence on the properties of neural network

Key words: Neural networks, Backpropagation algorithm, Mode classification, SampleTraining sample