Abstract: In order to improve the applicability and forecast accuracy of prediction method for water flowing fractured zone height in the condition of fully mechanized coal mining, based on the migration laws of overburden, taking key stratum position and whether it is damaged or not as criterions, combined with statistical experiential formula, a new method was proposed. If the main key stratum in the fractured zone is unbroken after extraction, the height of water flowing fractured zone equals to the distance of the key stratum to coal seam; if the main key stratum destroyed and there is not any inferior key strata, the height of water flowing fractured zone predicted by statistical experiential formula; if the main key stratum is destroyed and there is inferior key stratum, next round of judgment for the sub key layer is similar to the main key layer to complete the forecast and so on. Applications in many cases show that the new method has high applicability and high accuracy.