Abstract: The tax record and the boundary description are both important evidences in determining the property rights of mountain land. However, the importance of the two differs at different times. In the middle and late Ming period, tax reform diversified the livelihood model centred on forestry, making poll tax a fundamental basis of mountain land allocation in Lijia (“里甲”), while mountain tax became the legal certificate. In the early Qing period, with the practice of dividing the poll tax into land, Lijia lost its basis for allocating mountain land. As a result, the number of transactions and disputes increased. Against the backdrop of a booming forest economy, many family lineages strengthened joint control over the collective mountains through the prohibition convention for the restoration of the exclusivity of the mountain land boundary. The internal logic of this process of transformation is to move from the regulation of the tax system to the mechanism of the market. With the disappearance of the poll tax, the mountain tax is only used as a legal certificate. The mountain land transactions and the joint control of property rights by the family lineage mainly express the demands for economic rights. This change in the property rights of mountainous areas can be seen as the weakening of legal rights and the strengthening of economic rights.