The connection analysis was based on idealized fixed or pinned connection. In that case, analysis method and design procedure of steel frame were simplified and convenient, but it was not practical behavior of steel frame. On the other hand, AISC design code considering semi rigid connection shows efficiency in steel frame design. So, This paper studies the moment-rotation relation adopted by power model considering three parameters and we design steel frame considering semi rigid connection and develop structural analysis program. Then, results of numerical analysis are compared with those of the Midas program. Finally, we find that steel frame considering semi rigid connection is more efficient.