【Aim】 Based on the biological characteristics of stronger rooting ability of each internode in Mikania micrantha, a biocontrol technology that inhibits the expression of genes related to root growth by RNAi was developed, providing a foundation for further development of targeted control technology of M. micrantha. 【Method】 A key gene involved in the root development of M. micrantha (MmEXPA4) was identified by the homologous comparison method, and the double-stranded RNA (dsMmEXPA4) was further synthesized in vitro. Then, dsMmEXPA4 was injected into M. micrantha roots to investigate its effect on root growth. 【Result】 The number of adventitious roots and their fresh weight, and the length of the longest adventitious root under the dsMmEXPA4 treatment after 30 days were significantly reduced compared to those under the control condition. In addition, the gene expression of MmEXPA4 was significantly downregulated at days 4 and 5 post-injection. The silencing efficiency of dsMmEXPA4 was 43% on day 4 and 52% on day 5. Based on the Fluorescent Stereo Microscope Leica M165 FC images, it was found that fluorescently labeled dsMmEXPA4 could be detected through a strong green fluorescence signal in the root tissue. 【Conclusion】 The MmEXPA4 gene could be used as a potential target to inhibit the root development and rapid growth of M. micrantha, providing a theoretical basis for further development of biological control technology through RNA interference.