Abstract: To ensure fully mechanized caving face in the mining process free from the overlying aquifer influence in Zhuxianzhuang Coal Mine,Maximize the exploitation of the face as high as possible, coal pillar should be remained in reasonable safety thickness. Ground drilling observation method, underground electrical network parallel instrument detecting method along with the discrete element numerical simulation are adopted to study the law of fully mechanized caving thick unconsolidated strata height growth. The result shows that caving-height ratio from the measured is 4.14, and crack and mining ratio is 9.74. The results from the two detecting methods are basically consistent; there are certain differences between the caving-height ratio and the crack and mining ratio after the same seam mining, generally appearing small amplitude increases with the increase of mining height; with the advancing of working face, overburden failure evolved from the bottom to top, the equivalent lines of tensile stress of the maximum principal stress turn "arch" to "saddle", and water flowing fractured zone is the highest in front of coal wall and after the face, attention should be paid to prevent the aquifer damaged.