Abstract: By applying the technique of integral equation and the Guo-Krasnosel'skii fixed point theorem of cone expansion-compression type,the existence of positive solution is studied for a class of nonlinear fourth-order two-point boundary value problems,where the nonlinear term f(t,u,v) is allowed to be singular at t=0,t=1 and u=0,v=0.In mechanics,the class of problems describes the deflection of an elastic beam simply supported at left and clamped at right by sliding clamps.Because the nonlinear term concerns with the bending moment,main results is useful for the stability analysis of the beam.