Update publication Informatica. Alterations in gut microbiota have been implicated in the pathogenesis of Colorectal Cancer (CRC). Here we collected fecal samples from 14 CRC patients and 14 healthy volunteer cohorts, and characterized their microbiota using label-free quantitative metaproteomics method. We have quantified 30,062 gut microbial protein groups, 91，902 peptides, and 195 genera of microbes, among which 341 proteins were found significantly different in abundance between the CRC patients and healthy volunteers. Our study demonstrates that gut bacteria involve in CRC pathogenesis not only via taxonomy abundance variations but also functional activity changes.