Abstract: The bearing and supporting effect of the roof filling body is the key factor to maintain the stability of the stope in the process of underground stope. In order to further improve the parameters of min⁃ ing path in deep mining area of Jinchuan No. 2 mining area，the simple supported beam calculation model is adopted to carry out theoretical analysis on the stability of the roof of the road after expanding the section， and carry out field measurement of the stress deformation of the roof filling body of the downward approach in Jinchuan No. 2 mining area，and verify the maximum distributed load value and stress characteristics of the roof filling body of the road with different structural parameters during mining. The evolution law of stress and deformation of roof filling body during mining is revealed. The results show that the tensile stress of the bottom surface of the roof filling body is negatively correlated with the thickness of the bearing layer，and positively correlated with the width of the approach and the overlying load. When the width of the road is ex⁃ panded from 5 m to 6 m，the maximum tensile force of the hanging bar in the roof filling body is 17.38 kN， and the maximum tensile force of the main bar in the bottom network is 10.02 kN，which is less than the lim⁃it tensile force of the steel bar with a diameter of 12 mm，and the load rate is 51.1%，which is in a benign load state. The maximum tensile stress of the roof backfill in the horizontal plane perpendicular to the axial direction of the road increases from 0.220 8 MPa to 0.269 9 MPa，which is less than the ultimate tensile strength of the backfill body 0.53 MPa，indicating that the cemented backfill in the large section under the road roof will not be unstable and fail. The study can provide theoretical guidance for the stability of the stop⁃ ing road roof filling body and the design of the road section parameters.

Key words: large-section downward drift, roof stability, downward cemented backfilling method, simple-supported beam model, deep stope