Abstract: In order to study the influence of sulfate attack environment on the shear performance of grey brick masonry with hemp fiber-clay mortar, the shear resistance performance, failure mode and load-displacement curve of grey brick masonry were studied by simulating the capillary migration route of sulfate through the semi-soaking-dry-wet cycle test based on the experimental background of the salt concentration in the mortar joint of the actual brick cultural relic building.The results show that with the increase of the number of cycles, the flake and block spalling phenomena appear at the edges of the grey brick and mortar joint, respectively.The shear strength of the grey brick masonry in the sulfate environment showed a trend of first increasing and then decreasing.The shear strength reached the maximum at 9 cycles, and the shear strength decreased to the minimum of 0.032 MPa at 15 cycles, which was 33.33 % lower than deionized water group.The failure of the grey brick masonry specimens is characterized by brittle failure, and the failure mode of the bonding interface is mainly characterized by interfacial bond slip failure and mortar failure.The microstructure of the specimens before and after the cycle reveals that the accumulation of sulfate in the early stage of the cycle makes the pores of the specimens occluded, which can improve the shear performance of the hemp fiber-clay mortar brick masonry.At the later stage of the cycle, the pores of the specimen will be damaged, resulting in a decrease in the shear resistance.