Abstract. A kind of artificial neural network (BP-ANN) was used to classify the different kinks of apples with the reflected spectrum. The spectrum (from 460nm to 720nm) of some specks on the surface of the apples was measured with the spectrometer. A kind of BP-ANN with single hidden layer was devised to identify two sorts of the apples (the scar and the rotten) by the biological surface spectrum. To get the optimized parameters of the neural network, it was studied that the performance of the ANN with the different neurons numbers of the hidden layer, the different ranges of the output, the error of network with the different MSE(Minimum Squares Error) goal.