Large resultant forces take place at the beam-to-column connections in a steel moment frame. Besides, stress concentration may also occur due to shear lag. The design of a beam-to-column connection is therefore important for a steel moment frame. To date, the elastic design based on the analytical study of stress concentration has been exclusively employed for these connections of a steel bridge pier of moment-frame type in Japan. However, such a design approach is not practical against large earthquake. It is also noted that many existing connections have been found to suffer from fatigue cracks in recent years. In the present study, the effectiveness of fillets and haunches of various sizes is studied numerically for the reinforcement of a beam-to-column connection under ordinary and large cyclic loads.