Abstract: Support structure of air cooled condenser is a typical vertical hybrid structure whose stiffness and mass are non-uniform at vertical direction; torsion effect of the structure is obvious，earthquake response of the structure is complex．Research results show that the large-diameter and thin-walled reinforced concrete pipe columns are main lateral force resisting members in the structure，the damage of the structure is mainly concentrated on the bottom of the columns，structures earthquake resistance fortification is simplex． For lacking of systematic study on the seismic design method of this kind of structure，and little of its design cortents is involved in the national standards． In order to guarantee the safety of the support structure and equipment under earthquake action，based on the seismic behavior test of model structure and bearing capacity test of large-diameter and thin-walled reinforced concrete pipe columns， seismic design method and seismic measure are put forward to design support structure of air cooled condenser．