Abstract: A limit equilibrium analysis was used to calculate the factor of safety for the waste mass against possible translational failure along the underlying liner system.The landfill could be divided into three parts: an active wedge lying on the back slope that tended to cause failure,a passive wedge and retaining wall resting on the foundation or liner system that helped to resist movement.With the change of interwedge forces,the upper and lower bound solutions for the landfill stability,i.e.,Fmax and Fmin,could be readily determined using this method.The average factor of safety Fave was used in this paper,instead of the true factor Ftrue.It was shown that the differences between Fave and Ftrue were within 5% for all cases.Fmax increased with the increasing of internal friction angle of municipal solid waste φsw,however,Fmin remained constant.All the factors of safety Fmax,Fmin and Fave increased with the increasing of height of retaining wall H2 and the friction angle between the retaining wall and the liner system δDA.It was found that the retaining wall significantly affected the stability of landfill.