Abstract: In order to solve the problem of surrounding rock instability control of open-off cut road⁃ way of large-span soft coal side，taking the large-span open-off cut roadway of 12306 working face in Wangjialing Mine as the engineering background，the non-coordinated deformation and failure mechanism of roadway top and side under the original support condition is analyzed by means of field observation，in�situ stress test and borehole fracture monitoring. The results show that the strength of the coal body in the side is low，the plastic zone of the surrounding rock exceeds the range of bolt support，and the medium tec⁃ tonic stress field jointly induces the disaster of roadway bulging and spalling. Based on this，a collaborative control technology of strong side support + low disturbance step-by-step excavation is proposed. The length of the side bolt is extended to 2.5 m，the preload torque is increased to 300 N·m，and the excava⁃ tion process of the two pilot tunnels is optimized. Based on the micro-element algorithm，a quantitative characterization method of fracture density of borehole image is established. The monitoring data show that the average fracture rate of surrounding rock is reduced from 0.72% to 0.44% in the range of 4 m shallow coal. The maximum axial forces of the side bolts and the roof anchor cables are 56.26 kN and 116.86 kN， respectively，accounting for only 35.83% and 20.04% of their respective yield loads. The optimization scheme effectively improves the problem of non-coordinated deformation of roof and side，and the control effect of surrounding rock is good，which can provide reference for similar large-span soft coal side open�off cut roadway support project.

Key words: large-span open-off cut roadway, soft coal side, incompatible deformation, fracture char? acterization, support optimization