Abstract: Objective: To study the effect of β-nicotinamide mononucleotide (NMN) on the growth of Caenorhabditis elegans (C. elegans) and its mechanism. Methods: Nematodes were randomly divided into blank control group and experimental groups with different concentrations of NMN (0.1, 0.5, 1, 5, 10 mg/mL). The impact of NMN on the growth of C. elegans was evaluated by measuring the body length changes of C. elegans in 13 days after adulthood. In addition, transcriptomics was used to explore the mechanism of NMN (1 mg/mL) in promoting nematode growth. Moreover, quantitative real-time polymerase chain reaction (qRT-PCR) was performed to verify the sequencing results. Results: Compared with the blank control group, the average body length of C. elegans was significantly increased after feeding 0.1, 0.5, 1, 5 and 10 mg/mL NMN at 4 to 13 days (P<0.05). Totally 263 differentially expressed genes (DEGs) were identified by transcriptome sequencing analysis. Gene ontology (GO) analysis showed that these DEGs were mainly involved in cuticle development involving collagen, cuticulin-based cuticle molting cycle, collagen and cuticulin-based cuticle development, collagen trimer and other biological functions related to growth and development. The protein interaction network diagram was constructed for the DEGs in the enriched key GOs, then the top 10 key genes were screened out for qRT-PCR verification, and the results were basically consistent with the transcriptome. Conclusion: NMN may promote the growth of C. elegans by regulating the expression of collagen and cuticle related genes. This study provides new ideas for the development of functional foods and health products.