A static interval optimization method for structures was developed. The matrices of structures with interval parameters are given. Combining the interval extension of functions with the perturbation theory of static analysis, the method for interval static analysis of the structure with interval parameters and interval loading was derived. The Interval optimization problem was transformed into a corresponding deterministic one. Because the mid-values and the uncertainties of the interval parameters can be selected as the design variables, more information of the optimization results can be obtained by the present method than that obtained by the deterministic one. The numerical results show that the present method is valid.