Background We investigate the effect of long non-coding RNA (lncRNA) CCDC26 on the chemosensitivity of HCC cells to cisplatin and the underlying mechanisms. Methods Firstly, the expression of CCDC26 in HCC tissues was detected. After siRNA interference of CCDC26, the HCC cells QGY8105 and HCC9204 were selected as the objects of study to detect the changes in their chemosensitivity to cisplatin through the terminal-deoxynucleotidyl transferase mediated nick end labeling (TUNEL) and IC50 assays. Additionally, the RT-PCR assay, RNA hybrid software analysis, and luciferase reporter assay were performed to screen and verify the miRNAs that showed endogenous competitive relationship with CCDC26. Finally, miRNA was co-transfected with CCDC26, so as to explore whether the competitive binding of CCDC26 with miRNA changed the sensitivities of QGY8105 and HCC9204 cells to cisplatin. t-test or analysis of variance was adopted to compare data between groups based on the data property.. Results CCDC26 expression in HCC tissues was higher than that in normal tissues. Under the action of cisplatin, the IC50 value in si-CCDC26 group was lower than that in si-NC group, while the percentage of TUNEL-positive cells was higher than that in si-NC group, and the differences were statistically significant. RT-PCR results indicated that, miR-340 expression in si-CCDC26 group was up-regulated relative to that in si-NC group; meanwhile, RNA hybrid analysis and luciferase verification results demonstrated that there was base complementation between CCDC26 and the “seed” region of miR-340. Thereafter, miR-340 was co-transfected with CCDC26 into HCC9204 cells, and it was discovered that, the IC50 value in miR-340 + CCDC26-wild type group increased compared with those in miR-340 + NC and miR-340 + CCDC26-mutant groups. Meanwhile, the percentage of TUNEL-positive cells was reduced, and the differences were of statistical significance. Conclusions LncRNA CCDC26 can reduce the chemosensitivity of HCC cells to cisplatin through the endogenous competitive binding with miR-340.