The ‘凸’-shaped, the ‘呂’-shaped and the hexagonal-shaped pit houses were excavated at the Youngdong area, some location along the upper the Imjin River and Han River between the Iron age and the kingdom of Hanseong Baekje. The aim of this study is to analyze various structural system and developement of the pit house with rectangular plan. It is considered a matter in all its aspects which are plan, scale, aspect, pillar holes, carbonized wood and several traces. These pit houses removes the pillar on the inside or it reduces to secure a wider space, it pursued the chamfered corner, the change of the front, the entrance fixed. Also these adopted diverse structural systems(the chuandou structure, the structural system of columns and beams and a bearing wall). But in the course of time, the Korean wooden architecture is developed gradually the structural system of columns and beams. It is presumed the result that overcome the limit with the close space and pursue the flowing space and compose a group of organizable buildings.