The aging process of human colonic epithelium involves a slow decline in physiological vigor and an increasing susceptibility to age-related diseases, especially, colon cancer, but the molecular mechanisms of the aging and susceptibility of aged colonic epithelium to carcinogenesis is still unclear. Identification of aging related proteins in colonic epithelium will help to reveal the molecular mechanisms of colonic epithelial aging and age-related colonic diseases. Therefore, the total proteins of human normal colonic epithelial tissues from 10 young and 10 old men were separated by two-dimensional gel electrophoresis(2-DE), respectively. PDQuest software was applied to analyze 2-DE images, the differentially expressed protein spots of colonic epithelium between young and old groups were identified by matrix-assisted laser desorption/ionization time of flight mass spectrometry(MALDI-TOF-MS), and the expression levels of partial identified proteins were determined by real-time quantitative PCR and immunohistochemistry. Well-resolved, reproducible 2-DE maps of human colonic epithelial tissues from young and old men were established, 17 aging related proteins were identified by MALDI-TOF-MS, and the differential expression levels of partial identified proteins were confirmed by real-time quantitative PCR and immunohistochemistry. The results indicate that injury of mitochondrial function and decline of antioxidant capability are important reasons for the aging of human colonic epithelium, and four differential proteins (guanine nucleotide-binding protein beta subunit-like protein, stress-70 protein, 40 S ribosomal protein SA and chloride intracellular channel protein1) may be involved in susceptibility of aged colonic epithelium to carcinogenesis.