Abstract: In order to reveal the evolution mechanism of lateral abutment pressure at extra thick coal seam fully mechanized top coal caving face, taking Tashan coal mine 8206 working face as an engineering background, using the methods of similarity material test, numerical simulation and theoretical mechanical analysis, an end overburden motion model was established to study the features of end structure and the evolutional rule of lateral abutment pressure about goaf stability.Results show that before the goaf is stable the low key layer exists in the form of a cantilever beam structure and the high key layer exists in the form of masonry beam structure, and the peak value of lateral abutment pressure is 41.6 MPa, the range of influence is 68 m.After the goaf is stable, a triangular slip zone forms on the side of solid coal, and the peak value of lateral abutment pressure decreases to 32.09 MPa, although the range of influence increases to 99 m.The stability of blocks after the cantilever beam structure broke is mainly determined by height length proportion, broken angle and friction coefficient between the friction surfaces of broken blocks.And the root cause of the reduction of lateral abutment pressure is partial loads transferring to the goaf after the triangular slip zone stable, however, due to the effect of high abutment pressure before stability, it results in the influence scope of lateral abutment pressure increased after stability.