Aim To explore the regulatory effect of nicotinamide mononucleotide (NMN) on cholesterol in Huh7 cells and its molecular mechanism. Methods Huh7 cells were treated with different concentrations of NMN (0,2.5,5, 0,0, 200 μmol/L) for 24 hours, and the cell viability was detected by cell counting kit-8 (CCK-8). The lipid accumulation in cells was observed by oil red O staining. The uptake ability of cells to DiI-LDL was observed by immunofluorescence microscope. Quantitative real-time PCR (qRT-PCR) and Western blot were used to detect the expressions of mRNA and protein of intracellular hepatocyte nuclear factor 1α (HNF1α), proprotein convertase subtilisin kexin 9 (PCSK9), and low density lipoprotein receptor (LDLR). Results CCK-8 experiment showed that different concentrations of NMN had no significant effect on cell viability. Oil red O staining showed that the number of orange-red lipid droplets in the cells increased with the increase of NMN concentration after the addition of LDL. Immunofluorescence microscope observation results showed that the red fluorescence around the nucleus increased with the increase of NMN concentration. Western blot and qRT-PCR results showed that 100 and 200 μmol/L NMN significantly reduced the expressions of PCSK9 and HNF1α mRNA and protein, and significantly increased the expressions of LDLR mRNA and protein in Huh7 cells (P＜0.01). Conclusion NMN may be involved in regulating the cholesterol metabolism of Huh7 cells by mediating the HNF1α/PCSK9/LDLR signaling pathway, and enhance the uptake capacity of LDL by liver cells.