Abstract: To study the instability mechanism and supporting technology of deep-buried long-span coal roadway under composite roof, take the reconstructive transportation roadway of 2614 workface in a mine as a case study, the deformation law of roadway surrounding rock was analyzed by the theory of pressure arch and numerical simulation. The support scheme of “bolt (cable) + metal mesh +M steel belt + monomer pillar” was designed, and industrial experiments were carried out on site. The results show that the failure of the surrounding rock of long-span roadway under composite roof is composed of four stages: shear stratification, delamination, rupture and arching. The arc height of the roadway is 2.5 m to 3.8 m, the deformation of surrounding rock is less than 100 mm, and the anchor and cable tension are less than 60 kN and 350 kN, respectively. Besides, the pressure of the single hydraulic prop is less than 13 MPa, and the support effect is better.