Abstract: The existence of solution is considered for a class of nonlinear cantilever beam equations.In mechanics,the class of equations describes deformation of the elastic beam whose one end is fixed and the other is free.The character of this equation is that the nonlinear term contain third derivative of unknown function.By using of the decomposition of equation and the Leray-Schauder fixed point theorem,four existence theorems are established.The main results show that the class of equations has at least one solution or positive solution provided the "height" of nonlinear tem is appropriate on a bounded set.