The objective of this study is to examine the relations among the stability indexes and the effective length factors obtained from different buckling conditions. Total 96 two-span multi-story frames are examined, taking the condition of the column base, number of story, stiffness ratio, stiffness ratio reduction factor and distribution of the story shear as the parameters. Some of the findings are as follows: Effective length factors obtained by using the stability index agree with the exact factors about within 5% error, and the stability index obtained by G factor can be applicable as the stability index.