Star sensor is a kind of high-accuracy posture sensitive measuring system, how to confirm star sensor's photo-spot of corresponding fixed star at the moment of photography, that is stellar map recognition, it is the key of posture measurement. According as the specialty of stellar map recognition problem and the characteristic of the neural network technology, this article proposed a method of sample construction based on the method of stellar map recognition of the BP network. It can give consideration to the performance, efficiency and easy realization.