【Objective】Iron redox processes are important microbial processes, which are closely related not only to bioavailablity of heavy metals and degradation of organic pollutants in anaerobic environment, but also to soil fertility of upland soils. Therefore, the issue has aroused much attention the world over. Iron redox process in plough layers of paddy fields and upland fields was already well documented, however, it is still unclear whether iron redox process exists in the soil underneath the plough layers, or what are characteristics of the iron redox processes. 【Method】In the present study, samples of upland cinnamon soils, collected from different layers of a 0~100 cm deep soil profile, were prepared into slurries, separately and then incubated anaerobically in darkness or in light, 0.5 mol·L^-1 HCl extractable Fe(II) in the soisl samples was analyzed dynamically to study characteristics of the reduction and oxidation of iron oxide in the soil profile. To explore transformation of C, N and S coupled with the iron redox process in the profile, organic carbon, inorganic carbon, nitrate and sulfate in the profile soil samples before and after incubation were extracted by water and analyzed with a TOC analyzer and Ion Chromatography. 【Results】Fe(II) accumulation was found in all the samples during anaerobically incubation. Iron reduction potential decreased with soil depth in the profile. Fe(II) re-oxidation appeared only in the 0~80 cm soil layer of the profile under illuminated incubation. Ferrous oxidation decreased with depth in the profile from 20 cm to 80 cm. Water soluble organic carbon and iron oxide reduction both decreased with depth in the profile under incubation in light illuminated or in darkness. Water soluble inorganic carbon increased in the soil during the incubation in darkness, while it decreased in illuminated incubation. Water soluble nitrate decreased by 83.4%~98.6% in the soil incubated either in darknss or in light, and the range of the decrease narrowed with depth in the profile. The range of the decrease in water soluble sulfate narrowed with depth in the profile under incubation in darkness, while water soluble sulfate increased with depth in the profile within the range from 0~40 cm under illuminated incubation. Correlation analysis shows that iron reducing potential and ferrous oxidation was positively and significantly related to increase and decrease in water soluble inorganic carbon, respectively. Rate constant, max velocity of iron reduction and ferrous oxidation velocity was positively and significantly related to water soluble organic carbon. While decrease in nitrate was positively related to reducing potential, max velocity of iron reduction, re-oxidation and velocity of iron oxidation. Sulfate reduction was positively and significantly related to reduction potential, and max velocity of iron reduction under incubation in darkness, while it was negatively to amount and rate of ferrous oxidation under illuminated incubation. 【Conclusions】Results show that iron reduction process exists throughout the whole profile from 0 to 100 cm, and iron reduction potential, and maximum velocity of iron reduction decreased significantly with depth in the profile. Phototrophic ferrous oxidation appeared in the 0~80 cm soil layer in the profile; the amount and rate of ferrous oxidation was much higher in the 0~40 cm soil layer in the profile than in the 40~80 cm soil layer. Correlation analysis of iron redox process and soil properties in the vertical direction of the upland cinnamon soil shows that iron redox process in the profile was not only affected by soil organic carbon, but also limited by the contents of soil nutrients including N and K. The findings may help improve the cognition of the habitat of iron redox microbes, and serve as certain basis for in-depth understanding of the iron redox processes in upland cinnamon soil.