Monascus is a widely used natural microorganism in our country, which can produce useful secondary metabolites. Studies have shown that medium composition plays an important role in the primary and secondary metabolism of Monascus, especially the nitrogen source directly affects the growth, reproduction and secondary metabolites of Monascus. As a global transcriptional regulator of nitrogen metabolism, AreA gene is involved in the regulation of secondary metabolism. In this study, a MareA gene with high sequence homology to AreA gene was found by alignment analysis of the C100 genome. C100 knockout and overexpression mutants were obtained by Agrobacterium tumefaciens transformation. In this study, four nitrogen sources (Glutamine, Urea, NaNO ₃, (NH ₄) ₂SO ₄) were used to grow C100 and mutant strains. The yield of monascus rice under different nitrogen sources was compared by solid-state fermentation, and the types and yields of Mps produced were analyzed. HPLC and RT-qPCR were used to analyze the secondary metabolites of the three strains. Notably, growth differences between these monochorus strains were most pronounced when NaNO ₃ medium was added. The fermentation product yield and gene expression level of the knockout strain were significantly lower than those of the C100 strain, while the opposite was observed for the overexpression strain. In conclusion, MareA gene had different regulatory effects on monochorus growth and metabolism under different nitrogen sources.