Abstract: In order to study the effect of shear deformation on coal gas seepage,a true triaxial shear seepage test system was developed to solve the problem that shear seepage test was only affected by shear stress and normal stress in the past,as well as the sealing of gas seepage in shear process,experimental study on gas seepage flow under true triaxial shear deformation was realized.The true triaxial shear seepage test of briquette under gas pressure of 1 MPa was carried out by this system.The results showed that the briquette has obvious shear failure under the three-dimensional stress,the curves of stress,displacement and seepage flow have obvious correlation with time.The gas seepage shows a rapid decline and then a slow decline,the seepage velocity increases slightly after the shear failure occurs.The system provides a new test method for further research on the effect of shear deformation on coal gas seepage.