To investigate the effect of microRNA-7 (miR-7) over-expression on the growth of human lung cancer cells in vivo and in vitro and explore its possible mechanism.The eukaryotic expression vector of pcDNA3.1 encoding miR-7 (p-miR-7) was transiently transfected into human lung cancer 95D cells in vitro. The proliferation of cells was detected by MTT assay and colony formation assay. Moreover, the expressions of nuclear antigen Ki-67 and CGG binding protein 1 (CGGBP1) were detected by immunofluorescence assay. Human lung cancer model in nude mice was established. Next, p-miR-7 vector was directly injected into local tumor tissue. Then, tumor size was measured and the survival time of mice was observed. The expression level of miR-7 in the tumor tissue was determined by real-time PCR. Finally, the expressions of Ki-67 and CGGBP1 were detected by immunohistochemistry.Over-expression of miR-7 could significantly inhibit the growth of 95D cells in vitro (P<0.05), accompanied by the remarkably reduced expressions of Ki-67 and CGGBP1 (P<0.05). Moreover, compared with those in control group, the expression level of miR-7 increased significantly in p-miR-7 injected group (P<0.05). Meanwhile, the growth of tumors in injected group was slower than in the control group. Consistently, the survival time of mice was dramatically prolonged in p-miR-7 injected group (P<0.05). The expression levels of Ki-67 and CGGBP1 also remarkably decreased in tumor tissue (P<0.05).Over-expression of miR-7 could significantly inhibit the growth of human lung cancer cells in vivo and in vitro, which might be related to the down-regulated expression of tumor growth-associated protein CGGBP1.