Abstract: Geosynthentic clay liners (GCL) have great application value in canal lining projects. In order to estimate the effects of aging factors on the mechanical properties of GCL as canal lining materials, a series of laboratory simulation and field experiments in Inner Mongolian Hetao irrigation district were conducted to test effects of the five aging factors on the mechanical indexes of three kinds of GCL. The results indicated that temperature, humidity and ultraviolet radiation had some effects on the mechanical properties of GCL. The effects of high temperature on mechanical properties of GCL were more significant than those of low temperature, and the effects of high-low temperature cycling were weaker than effects of high or low temperature separately. Three kinds of mechanical properties of GCL samples was decreased by 34.27%, 35.77%, 45.02% after high temperature (60℃) aging 72 h and 19.51%, 31.49%, 18.40% after low temperature(－40℃) aging 72 h, 19.32%, 32.62% and 38.28% after high-low temperature cycling(－40℃ for 12h and 60℃ for 12h ) 10 times and 29.08%, 18.31% and 36.17% after Ultraviolet radiation 1200 h, respectively. The mechanical properties of 2 # and 3 # decreased by 12.41%, 13.08%, but 1# has no change with GCL moisture content from 50% to 100% after high temperature (60℃) aging 24 h. GCL in field aged faster in the first year, and the mechanical properties of the three samples decreased by 12.1%, 18.5% and 17.8% respectively while mechanical properties varied mitigatively after one year. This research can provide references for the application of GCL as canal lining materials.