Dissimilatory iron reduction is an important microbial process of the degradation of organic matter in anaerobic environment. It not only affects translocation of some inorganic pollutants, like Cr and U, but also is closely related to emission of greenhouse gases, such as CH₄, N₂O, H₂S, etc. Samples of cinnamon soils, collected from upland farmlands at 7 different locations, were prepared into slurry and then put under anaerobic incubation, to study characteristics of the anaerobic reduction of iron oxide in these soils. Results show that dissimilatory reduction of iron oxide occurred in the cinnamon soils under submergence, with reducing potential ranging from 4.47 to 5.95 mg g^-1 and a reduction rate constant between 0.15 and 0.27 d^-1. In the soils, a portion of crystalline iron oxide was reduced during the process and the mean reduction rate of free iron reached 41.95%. After 40 days of incubation, 99.26% of the NO₃^- and 88.82% of the SO₄^2- in the soils were reduced. And the rate constant, V_max and T_max of the iron reduction was positively related to soil organic carbon content, and the reducing potential negatively related to soil SO₄^2- content.