Abstract: Abstract：In order to effectively control floor heave of water-absorption-expansion soft rock roadway，the author have analysed floor heave mechanism based on double factors of loading and water conditioning. Pressure-relief was proposed to control floor heave.A mechanics model for pressure-relief was established. The method of determining the width of pressure-relief was given. The stress distribution and displacement of roadway surrounding rock at different depth of pressure-relief are studied by means of FLAC-3D software. The parameters of pressure-relief are further determined. Studies have shown that adoption of pressure-relief reduced stress concentration effect of roadway angle and transferred vertical stress of the floor to deep. It is the flexure deformation of the diaphragm wall of pressure-relief that absorb the deformation of the floor. Field application has shown that adoption of pressure-relief and pressure-relief parameters can control floor heave effectively.