Abstract: In response to the uncertainty of the coefficient of fragmentation and expansion of layered roof, by comprehensively considering the interrelationships between the coefficient of fragmentation and expansion, the allowable deformation of tunnel surrounding rock, the length of constant resistance anchor cable, and the depth of pre splitting of the cut roof, a segmented test plan was developed for the coefficient of fragmentation and expansion of the roof of 2-3002 tunnel as the research object. Underground on-site tests and mine pressure monitoring were conducted, and comprehensive analysis of the mine pressure data showed that when the coefficient of fragmentation and expansion was set at 1.31 and the charging coefficient was set at 300g/m, The construction difficulty of the constant resistance anchor cable with a length of 15.3m is moderate, and the pre cracking and pressure relief effect of the top cutting is obvious. When the reserved roadway is stable, the cross-section reaches 82.5% of the original cross-section, meeting the requirements for reuse as a belt conveyor roadway size, avoiding repair engineering.