Abstract: According to the information measured in different mining areas, the development law and features of the water conducted fractured zone under the con ditions of the fully mechanized top coal caving mining were discussed.Calculation formula for the max height of the water conducted fractured zone under the fully mech anized top coal caving mining was studied in the paper.The results showed that under the condition of the fully mechanized top coal caving mining, the developed heigh t of the water conducted fractured zone would be higher than the conventional coal mining and the fully mechanized slice mining and would be increased by 1.37 times and 2.31 times individually than the other two mining operations. The fractured height and mining thickness ratio of the fully mechanized top coal caving mining would b e basically the same to the fractured height and mining thickness ratio of the primary mining in the slice mining and the development pattern of the water conducted frac tured zone would be a saddle shape.During the fully mechanized top coal caving mining under the water bodies, the given calculation formula could be applied to calcul ate the max height of the water conducted fractured zone.