Abstract: At present, the filling technologies such as raw gangue and pneumatic pumping are usually used to fill the goaf of extremely thin coal seam, the design function of filling system is relatively single, and the linkage between multiple systems is lacking, so the intelligent separation of gangue and the continuous filling with the working face can not be realized. In order to solve the above problems, taking the 1901N fully mechanized working face of Great Wall Coal Mine of Ordos Xinkuang Group in Inner Mongolia Autonomous Region as the research background, the intelligent filling system of fully mechanized working face in extremely thin coal seam is designed. The system comprises a coal gangue intelligent separation and crushing and long-distance continuous transportation system, a continuous pumping filling system and a filling template support matched with the continuous pumping filling system. Firstly, the mined coal gangue is transported to a coal gangue intelligent separation and crushing system by a belt conveyor for separation, crushing and screening. Secondly, the coal gangue is transported to a mixer by a tubular belt conveyor for mixing to form concrete for filling. Finally, the coal gangue is transported to a filling port by a high-pressure pipeline for filling. Through the test, the best proportion of filling materials and the corresponding compressive strength standard value of each age are obtained, which are suitable for the fully mechanized working face of extremely thin coal seam in Great Wall Coal Mine. And the filling scheme is determined, which is mainly filled along the gob-side entry retaining and supplemented by the filling of the goaf behind the support. The field measurement results show that the system can simultaneously implement precise filling along the gob-side entry retaining and the goaf behind the support, improve the filling efficiency and the advancing speed of the filling surface, reduce the impact of dynamic load on the surrounding rock of the roadway, and control the deformation of the roadway effectively. The convergence of the two sides of the filling roadway and the maximum displacement of the roof and floor are 133.5 mm and 178.2 mm respectively, which are within the reasonable control range and meet the field application requirements.