Abstract: Local wall-thinning, which is a common defect on the surfaces of pipelines, can not only reduce the load-carrying capacities, but also cause the serious failure accidents of pipelines. To study the problem, a numerical method for evaluation of plastic limit loads is adopted in this paper. Based on a large number of computational examples, the effects of axial, circumferential, small and large area local wall-thinnings with different sizes on load-carrying capacities and failure modes of pipelines under internal pressure and in-plane bending moment are discussed.