Objective To observe the expression level of inhibitor of differentiation 2 (Id‐2) and matrix metalloproteinases‐9 (MMP‐9) in rectal cancer ,analysis the correlation of the expression level of them ,to study the relationship between the expression level of them and the clinical pathology indicators of rectal cancer .Methods Rectal cancer tissues and normal tissue adjacent to rec‐tal cancer were obtained from the rectal cancer resection of 56 patients with rectal cancer ,using immunohistochemical method to ob‐serve the expression level of Id‐2 and MMP‐9 in normal tissue adjacent to rectal cancer and rectal cancer and Spearman correlation test to detect the correlation between the expression level of Id‐2 and MMP‐9 ;then we analyzed the relationships between the ex‐pression level of Id‐2 and MMP‐9 and the index of rectal cancer clinical pathology .Results The positive expression rate of Id‐2 in the in rectal cancer tissues is more higher than that of normal tissue of adjacent to rectal cancer (73 .21% vs .48 .21% ,P<0 .05) . The positive expression rate of MMP‐9 in the in rectal cancer tissues is higher than that of normal tissue of adjacent to rectal cancer (71 .43% vs .44 .64% ,P<0 .05) .Spearman correlation test showed that there is the positive correlation between the expression level of Id‐2 and MMP‐9 (r=0 .393 ,P=0 .003) .The expression levels of Id‐2 and MMP‐9 in rectal cancer were correlated with the degree of tumor differentiation ,TNM stage and lymph node metastasis (P<0 .05) ,but had no differences between the elements of age and sex (P>0 .05) .Conclusion There is a close relationship between the expression levels of Id‐2 and MMP‐9 in rectal cancer and the occurrence and development of rectal cancer .Rectal cancer with the higher Id‐2 expression level may be the ways to achieve tumor invasion and metastasis through MMP‐9 as a facilitator .