Abstract: Objective To explore the diagnostic value of the serum miR-29a,COX-2 and MMP2 in patients with liver metastases from colorectal cancer. Methods The blood samples from 73 patients with colorectal cancer,who were divided into liver metastasis(LM) group and non-liver metastasis(NLM) group,were collected,and 30 volunteers with benign diseases were also enrolled and assigned into control(CTRL) group.The serum levels of miR-29a,COX-2 and MMP2 were tested by using RT-qPCR or Elisa assay. Results The serum levels of miR-29a,COX-2 and MMP2 of the LM group was significantly higher than those of the NLM group (t=4.122,P=0.000;t=3.008,P=0.004;t=2.376,P=0.011) and CTRL group(t=2.174,P=0.021;t=3.135,P=0.001;t=2.228,P=0.013),and the three indexes of the NLM group were significantly higher than those of the CTRL group (t=3.339,P<0.001;t=1.873,P=0.035;t=2.432,P=0.009).Logistic c regression analysis showed that the expression levels of the three indexes had the positive association with the liver metastasis of colorectal cancer(P<0.05).AUC value from ROC curve of miR-29a,COX-2,MMP2 and Y were 0.852 0.04,0.715 0.03,0.738 0.03,and 0.903 0.05,respectively(P<0.05).The combined three indexes had higher sensitivity,specificity and accuracy in diagnosing liver metastasis of colorectal cancer as compared with single index,which was 72.1%,94.6% and 96.8%(P=0.002). Conclusion The expression level of miR-29a,COX-2 and MMP2 have the positive association with disease status of colorectal cancer,and a high value in the diagnosis of liver metastasis.The mechanism between them may accelerate the deterioration of colorectal cancer.