Compared with wood, corn stover (CS) is a low-value raw material. Traditionally, CS is used in whole. To develop a CS high-value utilization process, the inhomogeneity of CS and its effects on bioconversion were investigated. The results showed that the chemical compositions of parts from CS had a remarkable difference. The Standard Deviation of cellulose, hemicellulose, Klason lignin, ash of CS parts (leaf, shell, core, node) were 3.09, 9.29, 3.32 and 4.58, respectively. The percents of fiber cell, parenchyma cell, epidermis cell and vessel cell were 30%, 30%, 10%, 30% (in leaf), 50%, 20%, 25%, 5% (in shell), 30%, 60%, 10% and 0% (in core), respectively. The inhomogeneity of CS chemical compositions and cell types affects its enzymatic hydrolysis and fermentation performances. The cellulose enzymatic hydrolysis ratio of corn core at 48 h was 130% higher than the leaf. After 7 d solid state fermentation, the filter paper activity of shell fiber, leaf fiber, core fiber, shell mixed cells, leaf mixed cells and core mixed cells were 40.6, 62.9, 64.1, 67.3, 194.2 and 154.0 IU g(-1) dry medium, respectively. The differences proved that the whole utilization process was unsatisfactory and suggested the potential of CS fractionation. Based the results, a pilot scale CS fractionation process (CS- Steam explosion-Water washing-Mechanical fiber fractionation-fiber cell and miscellaneous cells) was tested and divided corn stover into fiber cell and miscellaneous cells in the ratio of 1:1 approximately. The study showed the essentiality of CS fractionation and feasibility of fractionation by a simple method. (C) 2011 Elsevier Ltd. All rights reserved.