Abstract: As a simplified method for elastoplastic analysis, limit analysis method is more efficient and practical than the traditional increment method. In this paper, a self-equilibrium stress field in limit analysis is constructed based on Melan's theorem. The complex method is used to tackle the resultant nonlinear programming problem. The lower bound load multipler of two-dimensional structures is obtained. Numerical examples show that the present method overcomes the dimension obstacle and improves the computational efficiency of limit analysis.