Tree growth is affected by many exogenous and endogenous factors, especially climate and competition. To address the issue of how these factors influence tree growth under global warming, dendroclimatology combined with competition analysis was used to examine the radial growth response of two major species - Pinus massoniana and Schima superba in subtropical monsoon mixed forests in southern China. Growth-climate relationship analysis suggested that tree growth varied in response to climate and was mostly correlated with minimum, mean and maximum air temperature as indicated by adjusted R² value. Temperature of summer and winter represented negative effect on tree growth, while that of early spring showed positive effects. Competition analysis suggested that subtropical trees had been affected by competition in varying degrees, trees in the oldest forest had the most competition stress, while trees in younger forests were less affected by competition according to adjusted R² value. Subtropical forest in China would experience a decreasing effect of competition given these ecosystems have been found to have more smaller trees than larger ones with recent warming, which might have profound effects on forest productivity and carbon sequestration potentials in China subtropics.