Abstract: With the increase in use of mega-frame structures,the main frame beam-column reasonable arrangement becomes the key problem of a design.The results of a 24-story mega-frame structure with 4-span was calculated by the universal finite element program SAP 2000.At the condition of equal total section area of main frame beam-column,changing the size and number of main frame beam-column,the different structural free vibration periods,structural sways and structural moments were compared,the influence of main frame beam-column arrangement on behaviors of mega frame structures were discussed,and some reasonable suggestions were put forward to guide engineering practice.