Abstract: Biological properties of natural paddy soilsapplied with organic matters were studied by soil culture. The test results showed that soil biomass carbon was increased significantly by applying organic matters, the effects to soil enzymes were different in accordance with different enzyme species, paddy soils, organic matters and stages of rice growth. As far as the effect commonness of organic matters on enzymes of natural soils, organic matters had an inhabiting effect on the rising of urease and catalase activity in early stage of soil flooding, at the same time, polyphenol oxidase activity was enhanced rapidly, but declined in later stage of rice growth. Invertase activity and phosphatase activity were improved significantly. However, the effects of organic matters on dehydrogenase activity were reverse in the two soils.