Abstract: The law of strata behavior caused by fully mechanized caving mining face of super-long and thick coal seam is obviously different from that of traditional strata movement. In order to study the law of strata behavior in super-long working face, taking the first mining face of 14201 in Majialiang Mine as the engineering background, using the theory of fixed beam and cantilever beam, 3DEC numerical simulation and field observation, the characteristics of breaking and instability of roof are studied. The results show that the theoretical calculation of the first weighting interval of the main roof is 62.5 m, the periodic weighting interval is 25.54 m. The numerical simulation shows that the first weighting interval is about 60 m to 70 m and the periodic weighting interval is about 25 m, which is basically consistent with the theoretical calculation results. At the same time, according to the field monitoring data of hydraulic support working resistance, the research results are further verified.