Abstract: In order to obtain strata behavior regularity of fully mechanized top coal caving mining face in the extra-thick coal seam below 15 m in the very short-distance goaf, the first workface of 3-5^# coal seam in China Coal Energy Datong Tashan Coal Mine is taken as the engineering background, and through the use of microseismic monitoring technology and hydraulic support working resistance monitoring technology, the study obtained the following results: under the influence of overlying coal seam mining, the overburden strata shows the characteristics of “slow movement”; the overall compressive strength is small during the mining process of the working face, and the periodic weighting distance of the support is greater and the regularity is not strong; the working face strata appears as quasi-static pressure, and the working condition of the support is relatively stable. The dynamic load factor of the support during the periodic weighting is 1.19 to 1.22. The results could provide reference for safe and efficient mining of fully mechanized caving mining face in ectra-thick seam under similar conditions.