Objective: To investigate the effect of monoamine oxidase A(MAOA)MAOA c.1409 T>C synonymous mutation on anxiety, fear and other emotional behaviors in mice. Methods: In this study, CRISPR/Cas9 technology was used to construct a mouse model of SNP synonymous mutation, which simulated the C and T allele polymorphisms of rs11370770 in the population, and evaluated the differential effect of this gene on male and female differences through animal behavior and gene expression levels in animal models. In terms of animal behavior, open field test (OFT), elevated plus maze (EPM), defensive burial experiment (DBE), and 3D behavioral analysis were mainly used analysis) and other methods were used to evaluate the behavioral differences between male and female males caused by polymorphisms in Maoa synonymous mutant genes, and the MAOA content and enzyme activity in mice were detected to evaluate the effect of Maoa rs1137070 polymorphisms on gene expression in male and female SNP mice. Results: The results of the open field experiment showed that the residence time of female SNP mice in the central area of the open field was significantly higher than that of male SNP mice (P<0.001), the results of elevated cross maze experiment showed that the time and frequency of male SNP mice entering the open arm were higher than those of female SNP mice, but there was no significant difference, and the results of defensive burial test showed that the number and duration of excavation of female SNP mice were significantly reduced to the threat of rat urine (P<0.01). Three-dimensional fine behavior analysis showed that there was no significant male and female difference except for the movement trajectory and climbing behavior of mice. Compared with male SNP mice, the MAOA enzyme content of female SNP mice was significantly lower than that of male SNP mice (P<0.001), but there was no significant difference in enzyme activity between male and female SNP mice. Conclusion: The synonymous mutation of MAOA c.1409 T>C may cause fear, anxiety and mood differences in male and female mice by affecting the expression of MAOA in male and female SNP mice.