In practical design of an allotype high-tower, the conception of optimum design was introduced. And method of search-rule was used in the structural optimum design.Based on ANSYS, which is a finite-element method software, APDL (Ansys parametric design language) was extended to form an optimization program. The results have showed that this optimum program can not only lighten the weight of the structure, save material, simplify construction, but also remarkably improve the forced condition of the structure at the same time.