Objective:To determinate the of transmembrane protein endothelial factor(TPEF) and the 12th codon mutation of K-ras gene in plasma DNA Simultaneously,and to evaluate its feasibility in noninvasive diagnosis of colorectal cancer. Methods:DNA was isolated from plasma,the hypermethylation of TPEF was detected by methylation-specific PCR,the mutation of K-ras gene by mutation enriched PCR-RFLP method respectively. Results:Hypermethylation of TPEF was confirmed in 27 cases,and 12th mutation of K-ras gene was confirmed in 15 cases respectively in 42 colorectal cancer cases. Combined two molecular markers,the accord with the diagnostic rate of colorectal cancer was 76.2%. Conclusion:Simultaneous determination TPEF hypermethylation and K-ras gene mutation was an effective noninvasive method in screening and dignosis of colorectal cancer in the near future.