Objective To explore the mechanism of nucleophosmin (NPM) in HCC cells. Methods pEGFP/NPM was synthesized and transfected into HepG2 and SMMC7721 to stable high-expression NPM HCC cell lines. Cell counting kit-8 (CCK-8) assay was applied to detect cell viability; Wound assay and Transwell assay were used to detecte cell migration and invasion ability; the protein and mRNA expression of related genes were detected by Western blotting and real-time quantitative polymerase chain reaction (Real-time PCR). Results Cell viability [adriamycin (ADM): 8.31±0.89 vs. 0.38±0.13, P=0.000; 14.84±1.61 vs. 1.69±0.31, P=0.001; cisplatin (DDP): 4.23±1.18 vs. 1.33±0.29, P=0.047; 8.42±0.85 vs. 3.03±0.55, P=0.000, 5-fluorouracil (5-Fu): 20.75±1.02 vs. 7.97±0.97, P=0.001; 16.28±1.64 vs. 5.85±1.04, P=0.000], invasion and migration were increased in high-expression NPM HCC cell lines, and the expression of multidrug resistance 1 gene (MDR1-1: 3.85±0.67 vs. 0.97±0.22, P=0.043; 4.33±0.77 vs. 1.04±0.27, P=0.021), multidrug resistance-associated protein 1 (MRP-1: 3.76±1.04 vs. 1.01±0.21, P=0.033; 4.75±0.88 vs. 1.01±0.17, P=0.028) and permeability glycoprotein (P-gp: 2.06±0.27 vs. 1.04±0.19, P=0.000; 3.47±0.93 vs. 1.02±0.17, P=0.000) were increased. Conclusion NPM HCC cell lines expressed increased resistance to chemotherapeutic drugs, enhanced migration and invasion ability, and increased expression of MDR-1, MRP-1 and P-gp. Key words: Hepatocellular carcinoma; Multidrug resistance; Nucleophosmin; Permeability glycoprotein