China initiated a new collective forest tenure reform (CFTR) in 2003, which transferred the use rights of collective forest land and the ownership of collective trees to farmers. To assess the impact of the CFTR on timber production and to understand its underlying mechanisms, this study first conducted a theoretical analysis on how CFTR affects the production of commercial and non-commercial timber, leading to the provided hypotheses. Then, based on a panel dataset for 28 provinces from 1998 to 2018, a Time-varying Difference-in-Differences model was employed for empirical analysis. The results show that the CFTR led to an increase of 24.18% in commercial timber production and 34.37% in non-commercial timber production. The CFTR boosted the production of both types of timber initially, but the incremental effects were weakened over time. The incremental effects of the CFTR on commercial timber production was larger in regions with more collective forests. After the CFTR, the proportion of economic forest land in total forest land increased, contributing to a short-term rise in commercial timber production. In regions with higher timber market prices, reforms have a greater effect on increasing timber production, implying that farmers are more sensitive in their response to market values.