Abstract: On the background of one deep thick seam coal mine using fully-mechanized caving mining in Datong Coal Mine Group Co., Ltd., surrounding rock instability regularity and support scheme of deep mining roadway affected by dynamic pressure were studied with methods of surrounding rock geomechanics test, coal pillar stress measurement and reasonable coal pillar size determination. The study results show that mean compressive strength of roof coal, gritstone and No.4 coal seam is 32.08, 89.85 and 17.61 MPa individually. The maximum horizontal principal stress, the minimum horizontal principal stress and vertical stress of the measured area is 26.26, 13.39 and 15.80 MPa individually, direction of the maximum horizontal principal stress is N34.4°W, and in-situ stress filed belongs to high stress area on numerical value. During period of the first dynamic pressure, influence range and degree on coal pillar of advanced support pressure are far less than the ones of mining-induced stress after working face stoping ahead. During period of the second dynamic pressure, coal pillar located in 8-18 m borehole depth is in elastic kernel area, and reasonable coal pillar width is no less than 55 m. The initial support design of 14103 working face auxiliary transport roadway was proposed. The results of industrial field tests show that effective cross section area is 97.5% as large as excavation cross section after 14102 working face stoping ahead. During stoping 14103 working face, convergence between roof and floor in auxiliary transport roadway is about 300 mm, and convergence between two sides is about 260 mm, which can completely realize mine safety production.