The present study aimed to evaluate the function of microRNA (miR)-142-5p on cancer immunity to induce apoptosis in human non-small cell lung cancer (NSCLC) and its mechanism. miR-142-5p expression was upregulated, and CD4+ T cell levels were reduced in patients with NSCLC. Overexpression of miR-142-5p expression inhibited the cancer effects of CD4+ T cells on NSCLC cell lines, and downregulation of miR-142-5p increased the cancer effects of CD4+ T cells on NSCLC cell lines, compared with the control group. In addition, we found that overexpression of miR-142-5p suppressed PTEN protein expression and induced PI3K, p-Akt and PD-L1 protein expression in an in vitro model of NSCLC. Downregulation of miR-142-5p induced PTEN and PD-L1 protein expression and suppressed PI3K and p-Akt and protein expression in an in vitro model of NSCLC. The suppression of PD-L1 reduced the cancer effects of CD4+ T cells on NSCLC cell lines following miR-142-5p downregulation. The inhibition of PTEN also reduced the cancer effects of CD4+ T cells on NSCLC cell lines following miR-142-5p downregulation. Therefore, our study demonstrated that miR-142-5p regulated CD4+ T cells in human NSCLC through PD-L1 expression via the PTEN pathway.