The flat plate slab system have many good features, which are design flexibilities, saving of story-height and economy of construction etc. But the study of flat plate slab system for H-steel column have been rare both at home and abroad. Recently high-rise residential and commercial buildings have been constructed in urban areas in Korea. The suggested dowel connection system is more likely to adoptable because it remarkably contribute to save inter story height and also to have many advantages compared with conventional steel works such as H-Steel frame + Deck plate slab system. This study aims at developing design method and program for connection between H-Steel column and flat plate slab system, which contribute to save significantly inter-story height.