Bioreduction processes will influence distribution of metals in anoxic soil environments. To investigate distribution and evolution of iron and manganese in form in soils under long-term (~74 d) anaerobic incubation, reducing soil systems were simulated by setting up different ratios of glucose/humic acid for the soils in the experiment. Results show that at the initial stage of the incubation, addition of glucose prompted reduction and release of iron and manganese ions, and at the same time increased the amounts of exchangeable and acid soluble iron and exchangeable manganese. However, addition of humic acid increased the amounts of oxidizable iron and manganese in the soils. With the incubation going on, the concentrations of metal ions and the amounts of most various extractable forms of iron/manganese were decreasing, suggesting that the iron and manganese in the soil were gradually transformed into mineral phases lower in extractability. Therefore, it is quite obvious that in anaerobic environment, the reduction, release, distribution and transformation of iron and manganese are significantly affected by variety and concentration of the organic substances in the soil, resulting in variability of the metal elements in mobility and bioavailability in the environment.