The roof and floor of No.15 coal seam in Pingshu Coal Mine is mudstone, the deformation is serious in the process of roadway excavation, and the amount of maintenance work is large. Therefore, the deformation mechanism and control technology of soft rock roof and floor roadway are studied. Geomechanical tests on site show that the average strength of mudstone is 25 MPa, which is low in strength and poor in self-stability. During the excavation process, the roadway presents nonlinear deformation characteristics, the roof deflection sinks, and the floor heaves. The analysis shows that the lithology of roof and floor and the influence of residual abutment pressure in 15302 working face are the main reasons for the severe deformation of roadway. On this basis, the anchor cable truss support structure is proposed. The anchorage point of the structure is stable, and a relatively stable arch bridge belt can be formed on the roof to improve the bearing capacity. The structure is flexible and can adapt to the roof deformation. It is an effective support method for soft rock roadway. The field application shows that the support scheme effectively controls the deformation of the soft roof and floor roadway in the air intake gateway of 15304 working face, which provides a reference for the support of soft rock roadway under similar conditions.