Abstract: The probabilistic properties of the extreme value of environmental factor are described by the maximum entropy distribution for its excellent adaptability. Because LS-SVM has some important properties such as good generalization and excellent learning, it is employed to calculate the moment of the environmental factor according to short-term observation data and based on the extreme value samples obtained by Bootstrap method. The parameters of maximum entropy distribution can be calculated by the moments, so a new method for the distribution of the environmental factor based on short-term observation data is obtained. The method is verified by simulation experiment and actual data.