Abstract: Goaf water always seriously threatens the safe production in many coal mines in China. This paper takes the third water-accumulating section of 12226 working face's goaf in Xieqiao mine as an example. By comparison of the predicted and actual amount of goaf water, and with the analysis of lithology combination characteristics of roof and floor, the research obtained the relationship between the caving structure and water filling characteristics of goaf, and between the roof lithology and coefficients of water filling and expansion. The method and results will provide a new way of thinking and new methods for correctly predicting the amount of goaf water under similar conditions in the future.