Objective To explore the related genes that play a key regulatory role in cisplatin resistance in lung adenocarcinoma. Methods Bioinformatics methods were used to download the differentially-expressed genes between cisplatin sensitive group and drug resistant group in patients with lung adenocarcinoma in TCGA database and GDSC database. GO function analysis and KEGG pathway enrichment analysis were carried out to analyze the differentially-expressed genes. The protein-protein interaction network was constructed and hierarchical cluster analysis was carried out to screen the key genes. The key genes were verified at the cell level by real-time fluorescence quantitative PCR and ELISA. Then the expression of the selected key gene in A549/DDP cells was silenced by siRNA and its sensitivity to cisplatin was detected. Results We screened out 178 differentially-expressed genes. After cluster analysis, CXCL9, CXCL10, NKX2-1 and SFTPA1 were regarded as the key genes of cisplatin resistance in lung adenocarcinoma. CXCL10 was temporarily selected for subsequent verification and function experiment. The mRNA expression of CXCL10 in A549/DDP cells was significantly higher than that in A549 cells (P < 0.001), and the expression of CXCL10 protein in the supernatant of A549/DDP cells was higher than that in A549 cells, which were consistent with the prediction of bioinformatics. The sensitivity of A549/DDP cells to DDP increased after silencing CXCL10 expression. Conclusions CXCL10 is a key gene to regulate cisplatin resistance in lung adenocarcinoma. Downregulating the expression of CXCL10 can become a potential target for reversing cisplatin resistance in lung adenocarcinoma.