Objective：This study aims to construct a recombinant plasmid expressing fat mass and obesity associated（FTO）gene and to detect its effects on m6A modification and proliferation of mouse mesangial cells（MMCs）. Methods：The FTO gene fragment was amplified by PCR and inserted into the expression vector pCMV-MCS-EGFP plasmid to construct the recombinant plasmid pCMV-FTO. The target plasmid pCMV-FTO and the control plasmid pCMV were transfected into MMCs，respectively，and the mRNA expression of FTO was measured with real-time quantitative PCR（RT-qPCR）. The total protein was extracted，and FTO，EGFP，proliferation markers of Cyclin D1 and PCNA were detected by Western blotting. The proliferation of MMCs were studied with CCK8 method. The m6A content was measured using the m6A RNA methylation quantification kit. Results：Colony PCR identification and sequencing confirmed that the recombinant plasmid pCMV-FTO was successfully constructed. The results showed that the mRNA and protein level of FTO was significantly increased after transfection of the target plasmid pCMV-FTO. After overexpression of FTO，m6A content，the proliferation of MMCs and Cyclin D1，PCNA protein levels decreased significantly. Conclusion：FTO can reduce the level of m6A modification and inhibit cell proliferation in MMCs.