The basic pattern recognition theory of artificial neural network is introduced.The identification system for the oil′s three-dimensional fluorescence spectra is established based on the principal component analysis (PCA) and BP neural network method,and the system design and the basic frame of model are made.PCA was inducted to pre-analyze the feature parameters of oil′s three-dimensional, the principal components of original variables were used as the input of network, then the network output realized the identification of oil′s three-dimensional fluorescence spectrum. This method can cut down the dimensions of original input,eliminate the relativity between variables,at the same time simplify the network structure,and improve the convergence speed.Actual instance was tested effectively that the PCA-BP neural network compared with the normal neural network reduced training time and possesses better performance. Results showed that the method can be used to realize the identification of oil's three-dimensional fluorescence spectrum.