Abstract: Based on the theory of finite derormation, the general relation ship between deformations and strains of a thin-walled curved beam are derived in this paper. And then inquired in to the configuration of lateral-torsional buckling on thin-walled curved beams,along with taking in plane deformation into accornt, the basic differential equations of stability analysis for curved beams are also derived by the variational principle. The stability analysis shows that lateral-torsional buckling may be possible eventhough a curved beam is loaded in its original curved plane and bending round its weak axis. A curved beam with very small curvature is considered as a straight beam having initial curvature in this paper, so that the effect of the original curvature on lateral-torsional buckling strength can be accurately studied, Finally,the closed solutions given in this paper are compared with the ones obtained by Timoshenko,Vlasov and Yoo,and the sources of discrepancies are traced.