Abstract: Free-form space structures should satisfy the specific geometric configuration requirements and have the rational mechanical properties.Combining geometrical characteristics analysis and mechanical properties optimization,this paper proposes a modeling technique for free-form space structures based on equilibrium characteristics of natural tension membrane.To establish the proper objective surface which meets the given boundary conditions,the initial quasi-uniform B-spline surface is treated as tension membrane and optimized by Laplace equation and modified dynamic relaxation method.Numerical experimental results demonstrate that the proposed modeling technique is convenient and feasible,and it is effective for shortening the design period of free-form space structures.