Dynamics and transformation of dissolved organic carbon (DOC) in paddy soils of the red soil region were studied by sampling analysis and laboratory incubation. The results showed that DOC content decreased significantly with soil depth. DOC content and DOC/TOC(%) in 0~30cm layer increased with soil organic carbon content. Irrigation and rainfall could increase soil moisture. As a result DOC was 1.44 to 2.5 times higher under irrigation (submersion) than drainage (aerobic condition). During the 49 days of incubation, decomposition rate of DOC was 31%~58%, which differed from soils. Low molecular fractions could be mineralized in a few days.