Disordered tumor cell metabolism is involved in the process of tumorigenesis. Proline metabolism is of critical importance for tumor cells, and pyrroline-5-carboxylate reductase 1 (PYCR1), a key proline biosynthesis enzyme, has been reported to be overexpressed in prostate cancer and to promote tumor cell growth in breast cancer. The present study investigated the relationship between PYCR1 and non-small cell lung cancer (NSCLC). The results revealed that PYCR1 was overexpressed in NSCLC tumor tissues compared with adjacent normal tissues. High PYCR1 expression was associated with poor prognosis in patients with NSCLC. Following knockdown of PYCR1 by small interfering RNA, cell proliferation was revealed to be significantly inhibited and the cell cycle was arrested, while apoptosis was increased in SPC-A1 and H1703 NSCLC cells. Furthermore, the silencing of PYCR1 resulted in the downregulation of expression of the cell cycle regulator cyclin D1, the regulator of the mitochondrial apoptotic pathway B-cell lymphoma-2, and B-cell lymphoma-extra large. The results of the present study indicated the involvement of PYCR1 in the proliferation and apoptosis of NSCLC. Therefore, PYCR1 may be a novel therapeutic target for inhibiting cell proliferation in lung cancer.