At present ,there are many errors in fault identification of photodetectors. In order to improve the effect of fault identification of photodetectors ,a fault identification method of photodetectors based on pattern recognition technology is designed. Firstly ,the state signal of the photodetector is collected ,and the features are extracted from the state signal of the photodetector. Then the principal component analysis algorithm is used to reduce the dimension of the features to obtain the optimal photodetector state identification feature. Finally ,the photodetector state feature is used as the input of the support vector machine ,and the photodetector state is used as the output of the support vector machine. The photodetector state identifier is designed through the support vector machine learning ,The experimental results show that this method can effectively identify the fault of the photoelectric detector ,the correct rate of the fault identification of the photoelectric detector is more than 90% ,and the fault identification time of the photoelectric detec- tor is controlled within 20 ms ,which provides a basis for the status analysis of the photoelectric detector.