Abstract: To improve and optimize the stability analysis method of engineering slope with liner composed of geomembrane(GM) and geosynthetic clay liner(GCL),a simple method for determining the shear strength of GM+GCL composite liner is proposed based on the comprehensive analysis of the existing shear test results.By summarizing and analyzing the shear failure mode, peak and residual shear characteristics of GM+GCL composite liner under the normal stress covering low to high pressure, a selection principle for shear strength of the composite liner is proposed, which considers the double interfaces as a whole.Considering the characteristics of failure surface transfer and post peak softening of the composite liner, a specific simple method determining the peak strength and residual strength of the composite liner is presented.This study develops the calculation methodology for the shear strength of the slope containing geosynthetics.It can achieve rapid engineering safety analysis while reducing or saving a large amount of time and energy used in the shear tests of GM+GCL composite liner.