[en] In this work, the optimal design method for self-supporting transmission tower is put forward, whose procedure is that the tower body form is selected intelligently firstly and then the members types of tower are chosen. The case base of towers is established with application of object-oriented technology. Then, the knowledge of tower body is mined out with case based reasoning and data mining technology. At the same time, the structural regulations of tower in the standard are merged into the knowledge base. So, the intelligent selection system of tower structural scheme based on case reasoning and data mining is explored. A 500kV self-supporting tower is optimized according to above method and a real model test is conducted. Comparison between optimal tower and original tower indicates that weight of optimal tower is decreased by 3% and its ultimate bearing capacity is increased by 19%. Statistical analysis results of 20 optimal towers indicates that the weight is average reduced by 4.7%, the components of the optimal tower are stressed more uniformly and bearing capacity of the tower is enhanced 12% at least. (paper)