Objective To explore the status of mutations of k-ras gene in colorectal cancer (CRC) patients and to make theory preparation for the k-ras mutation detection in diagnosis laboratory. Methods The Genomic DNA was extracted, mutation analysis of k-ras was detected by PCR and bi-direction sequencing in the 56 specimens. Results Rate of k-ras mutation was 46.63 % (26/56) including 76.92 % (20/26) located at codon 12, and 23.08 %(6/26) located at codon 13, and no mutation was found at both codons simultaneously. G>A transition is the most common type of k-ras mutation,GGT>GAT (G12D) is the predominant mutation at codon 12 and GGOGAC (G13D) at codonl3. Chi-square analysis revealed the k-ras mutation was significantly correlated to the gender of the patients. Conclusion The k-ras mutation is mainly located at the codon 12, G>A transition is the most type of k-ras mutation in CRC. k-ras mutation seems to correlate with the gender of CRC patients.