When the people talks about the theory of co-ownership is always building the basis on the rule of each co-owner in Taiwan, because of the rule of ownership-in-common in Civil code is broken and fewer than the each co-owner's. However, the rule about co-dominant property of somepeople's re1ationship like partnership, the community of property is constituted by the husband and the wife and co-succesion also use the rule of ownership-in-common. Apparently, the rule of ownership-in-common has its own independent and integral theory architecture different from the rule of each co-owner. Therefore, the interesting question that the article aim to research arises is what The architecture of the theory of ownership-in-common in civel code. Besides, the research about remove the restriction on transaction order in civil law is help to understand why the property law's core from ownership to property.