Abstract:In order to understand the changing trend of groundwater level in a coal mine, combining with factual examples, and contrasting the results gained by using recursive filtering method and non-recursive filtering method respectively, the changing rule and the mechanism of groundwater level have been studied. It is showed that the adjustment of filtering coefficients will effect filtering results. According to the smoothness index, the root mean square error and the signal-noise ratio, and comparing with the existing observation time series of groundwater level, it is concluded that the recursive filtering effect is better when b=0.5, while the non-recursive filtering effect is proper when q=5. The filtering results can be used as the basis for predicting the changing trend of groundwater level in the future. It also can provide some references for the safe production in the coal mine.