Reinforced soil is a new economical and dependable method of slope reinforcement. Aimed at problems new type reinforced soil slope brought and the shortage of limit equilibrium method based on vertical slice, a rigorous approach based on horizontal slice for limit equilibrium analysis method is presented, in which the reinforcement force was assumed horizontal and failing at its maximum tensile strength. Limit equilibrium method based on horizontal slice divide slide body into horizontal slices, regards the resistance of reinforced material as additional outer forces, and then apply assumptions of limit equilibrium method to analyze forces acting on slices. Status of typical slice is analyzed, and implicit expression is derived by utilize of force equilibrium. The coefficient of interslice force is solved through moment equilibrium, and ultimately the real safety factor is approached iteratively. Bearing capacity of slope is also studied. Case study shows that the result of the method presented is a little bigger than classic limit equilibrium method.