【Objective】How to reasonably use of corn stover has become an important topic in the agricultural regions of China. Corn stover incorporation into the field is the best way in corn stover utilization. However, the method of corn stover incorporation used to either overcast the corn stover on the surface of the field like mulching or incorporate the corn stover into the shallow topsoil layer, which would obviously bring about some problems, like impeding rise of soil temperature, seedling growth, favoring incidence of insect pests. Corn stover deep incorporation (CSDI) refers to burying corn stover deeply into the subsoil layer and it is believed to be a sustainable utilization model to solve the problem of burning of corn stover and degradation of soil fertility. But with the days going on, it is not clear that the dynamic change in composition and structural characteristics of soil humus caused by CSDI. This paper mainly deals with the effect of the corn stover applied duration on components of soil humus and structural characteristics of humic acid in the soil, so as to provide some theoretical basis for determining the interval of CSDI.【Method】A field experiment was conducted in a mono-cropping corn field of black soil at the Experiment Station of the Jilin Agricultural University, with four treatments, that is, CK (No corn stover incorporated), CSDI-2014 (One year after the corn stover deep incorporation), CSDI-2013 (Two years after the corn stover deep incorporation) and CSDI-2012 (Three years after the corn stover deep incorporation). Humus, including fulvic acid (FA), humic acid (HA) and humin (HM) with the modified humus component extraction method for analysis of composition and then HA was further extracted with the IHSS method for analysis of element composition, infrared spectrum, thermogravimetry, and structure with differential thermal analysis. 【Result】Results show that in Treatment CSDI-2014 significantly increases the content of organic carbon by 23.7%, 30.5%, 27.3% and 46.1% in the soil, HA, FA and HM, respectively, and especially in the subsoil; but it did not affect PQ much; however, it reduced condensation degree and oxidation degree of the HA significantly and (O+S)/C ratio by 14.31% and 14.68%, while raising H/C ratio by 27.74% and 28.86% in the topsoil and subsoil. Moreover, it increased the content of aromatic-C and aliphatic chain hydrocarbon, reduced thermal stability and made simpler the structure of HA. The effects, however, varied with the time going on, in Treatment CSDI-2012, organic C decreased in content in the soil, FA and HM, but increased in HA, while PQ changed significantly; HA displayed an increasing trend in condensation and oxidation degrees and became lower in aliphaticity, higher in aromaticity, and more complicated in structure. 【Conclusion】With the days going on, the deep-incorporated corn stover in the soil gets mineralized and decomposed steadily, weakening its effects on composition of the soil humus and structural characteristics of the humic acid in the soil.