For exploiting green ecological cotton fiber products with the multifunction, a new cotton fiber crosslinked with chitosan of low molecular weight (CCCF) was prepared through the sodium periodate oxidation method. The reaction between amino groups of chitosan and aldehyde groups in the oxidized cotton cellulose occurred to obtain the CCCF in aqueous acetic acid solutions. The aldehyde group content in oxidized cotton cellulose increased markedly with the sodium periodate concentration, and the maximum weight gain of chitosan introduced on cotton fiber was 11.63% of the weight of cotton fibers. Furthermore, the crosslinking properties were respectively investigated by measurements of FT-IR and XPS spectra, the analysis indicated that the chitosan molecule was crosslinked on the surface of cotton fiber by the C=N covalent bond. This resulting CCCF is a novel ecological fiber and has more abilities of potential modification, which suggested useful information in planning applications for these modified cotton fibers.