A large number of studies have analyzed the annual growth rings and environmental drivers in subtropical China. However, how environmental and physiological effects define the isotopic composition of the wood in this region is poorly understood. Here, we explored the potential of applying three components (whole wood, holocellulose, and α-cellulose) of stable carbon isotopes from Masson pine (Pinus massoniana Lamb.) to dendroclimatology. Sampling sites were covered at the northern, eastern, southern, and western margins of the Masson pine distribution in subtropical China. The results showed that the mean δ¹³C of holocellulose and α-cellulose both had more enriched values than whole wood, with differences of 1.261 ± 0.233‰ and 1.311 ± 0.189‰, respectively, within individual trees. The three components displayed uniform year-to-year variations and common significant climatic signals, indicating that the δ¹³C of whole wood from Masson pine was enough to reconstruct interannual paleoclimate information without cellulose isolation due to its high climate sensitivity and low time requirements. The mean δ¹³C record was significantly and negatively correlated with autumn hydroclimatic parameters (e.g., relative humidity and precipitation) in each study area. This study provides evidence of the influence of hydroclimatic variation on Masson pine forests at a large spatial scale and further enhances the interpretation of climate variations.