The deterioration of shear properties of schist under dry-wet cycles has an important effect on the long-term stability of schist slope.Taking the mica-quartz schist widely distributed in Northwest Hubei as the research object,a series of laboratory tests were carried out to reveal the law and mechanism of its shear deterioration.The results of water absorption tests and direct shear tests show that the water absorption of mica-quartz schist increases,while the shear strength and residual shear strength decrease gradually with the increase of the number of dry-wet cycles,and the shear properties show obvious deterioration effect.Based on the changes of mica-quartz schist microstructure obtained by scanning electron microscopy,the deterioration mechanism of mica-quartz schist is revealed.Under the action of dry-wet cycles,the schist plane gradually expands and cracks,the strength of internal mineral particles is softened,the cementation between particles is weakened,and the rock skeleton becomes loose.What's more,the cohesion is mainly affected by the degree of cementation between mineral particles,so the deterioration rate is fast.While the internal friction angle is mainly affected by the degree of embeddedness and the strength of mineral particles,so the deterioration rate is relatively slow.