This paper discussed the application of Fuzzy ARTMAP neural network in land cover classification in Xianghai Nature Reserve. The structure and algorithm of Fuzzy ARTMAP neural network were described in detail, and an automatic adjustment method of vigilance parameter was put forward to solve the problem of searching the optimum value in the selection of vigilance parameter. The results showed that the automatic adjustment method could adjust network parameter automatically, and improve the running speed of network. In comparing with maximum likelihood classification method and traditional Fuzzy ARTMAP neural network, the Fuzzy ARTMAP neural network with the functioning of automatic adjustment depended less on samples and had higher accuracy, and thus, could effectively make the classification of TM image covering Xianghai Nature Reserve. It's shown from the classification that in the Xianghai Nature Reserve, farmland covered large area while grassland and marsh were facing degradation, and hence, corresponding countermeasures should be taken to improve the eco-environment of this Reserve.