Abstract: To prevent translational failure along the liner system is the most important issue for the modern landfills. The critical liner interface with the minimum factor of safety usually is not located at the same interface at the base and back slope. The critical interface can change from one to another with the waste height. When the waste height is low, the leachate head of 30 cm can make a relatively large effect on both the factor of safety and the critical interface. This effect will decrease with the increase of the waste height. The increase of the leachate head in landfills makes the decrease of the factor of safety rapidly and causes the changes of the critical interface. It is important to maintain the leachate head at a low and safe level and ensure that the minimum factor of safety at the critical interface is always equal to or greater than a targeted value during the filling sequence corresponding to different geometric dimensions of the waste.