The study find the interface construction is almost the same as the original by researching types of trusses, slopes, spans, dimensions of components, materials of wooden trusses and walls, roofs, ceilings. And the study systematize the local construction in Taiwan which is different from the historical materials and books about construction mentioned. The conclusions are as follows: 1、The system of western wooden trusses in Taiwan. it includes the basic information of Taiwan western wooden trusses, such as style, slopes, spans, dimensions of components, materials. 2、The interface construction system of western wooden trusses in Taiwan. it includes two part: the first is the method to construct the Taiwan western wooden trusses. The second part is about two kinds of interfaces one is between trusses and walls, and another is between trusses and eaves. Finally, the study suggests that when conservation works are carrying on, dimensions of trusses components should be recorded in detail.