The purpose of this study is to detect the clinical significance of NDRG1 and its relationship with MMP-9 in gastric cancer metastatic progression. 101 cases of gastric cancer specimens were utilized to identify the protein expression of NDRG1 and MMP-9 by immunohistochemistry, their clinical significance was also analyzed. The suppression by siRNA-NDRG1 was employed to detect the role of NDRG1 in gastric cancer progression and its relationship with MMP-9. NDRG1 expression was correlated inversely with the degree of tumor cell differentiation ( p  < 0.01), invasion depth ( p  < 0.05), lymph node metastasis ( p  < 0.05) and TNM stage ( p  < 0.05), whereas MMP-9 was positive correlated with the degree of tumor cell differentiation ( p  < 0.01), lymph node metastasis ( p  < 0.05) and TNM stage ( p  < 0.05), but not correlated with invasion depth ( p >0.05). Furthermore, cell proliferation and invasion effect were remarkably enhanced when NDRG1 was silencing, but MMP-9 expression was increased. NDRG1 silencing enhances gastric cancer cells progression through upregulating MMP-9. It suggests that NDRG1 may inhibit the metastasis of gastric cancer via regulating MMP-9.