The leaching of dissolved organic matter (DOM) from leaf litter, and the subsequent supply of an available carbon pool for microbial growth, can be important factors regulating forest C mineralization. Field studies have shown that with increasing DOM, soil respiration rates increase observably. Numerous studies have assessed the difference of dissolved organic C (DOC) and the C chemistry of solubility during leaching of DOM from different litters. The chemical structure of DOM and the complexity of its molecules were found to correlate with C mineralization. Our objectives were to investigate how differences in chemistry of DOM from Cunninghamia lanceolata and Castanopsis carlesii leaf litter affected soil CO₂ fluxes in laboratory incubations. Mineral soils from a depth of 0-10 cm from a 39-year-old C. carlesii plantation forest in Sanming, Fujian, China were incubated for 2 months after adding the same concentrations and amounts of DOM from C. lanceolata and C. carlesii leaf litter. CO₂ production was continuously measured during 59 days of laboratory incubation, and soil CO₂ evolution patterns were determined by fitting the double exponential model (r²=0.99). Results showed that: (1) C chemistry varied significantly between DOM from C. lanceolata and C. carlesii leaf litter (P < 0.05). UV and fluorescence spectra of DOM from C. lanceolata leaf litter were lower than those of C. carlesii leaf litter, which suggested that DOM from C. lanceolata leaf litter has a lower content of aromatic C. (2) Following additions of DOM from C. lanceolata and C. carlesii leaf litter to soils, rates of C mineralization increased by 198% and 168%, respectively, decreased to 61.8% and 44.1%, respectively, by day 3 and then decreased progressively. This indicated that an increase in soil C mineralization induced by the addition of external DOM to soil was short-term. (3) There was no significant difference in the cumulative mineralized C between the addition of DOM from C. lanceolata and C. carlesii leaf litter. Further research should be done to investigate the reasons for this lack of a significance difference.