A dwelling house is the most popular built type and the most common sort of building that people are close to. The external environment affects the form and space of dwelling houses directly. By analyzing the transformation of house forms, we can realize that when people move and relocate to other place, they will build their houses in different forms to follow the changing times. However, the biggest problem in research is that it is hard to know the construction date of each house. Therefore, the primary task is to confirm in what year the houses were built. Frequent relocation in Penghu left various houses in different forms during the Japanese colonial period. Few houses built in the Qing Dynasty remain at the settlement. Based on the related data, the construction date of Lin Family’s Ancient House at Tongliang is before the 36th year of Qianlong reign, during the Qing Dynasty (1711). These days is rare to see this kind of building, old but well-preserved, in Penghu and its’ materials are not used in and after the Japanese colonial period such as large horseback roofs, wood eave brackets and Wang Jia. The most inspiring discovery is that the deeds of the house and Lin’s family tree are still preserved; these sources are enough to prove the construction date of the building and have greatly contributed to the research into the transformation of house forms. According to the above reasons, the author introduces Lin Family’s Ancient House at Tongliang first and then compares the house’s form with other existing Penghu traditional houses. By doing this, the author probes the process of transformation and factors which made the transformation.