Abstract: To explore the effect of miR156 overexpression on the rooting of Betula platyphylla cuttings, B. platyphylla was used as the material, and the 254 bp fragment containing the mature sequence of miR156 was constructed on the pGWB2 plant overexpression vector using Gateway technology. The genetic transformation was carried out by agrobacterium-mediated method, and 8 miR156 overexpression transgenic lines were obtained; softwood cutting was carried out on non-transgenic control line and transgenic lines, and the adventitious root formation process of over expressed lines was dissected and observed by paraffin section, so as to analyze the effect of miR156 on cutting rooting. The results showed that the adventitious rooting rate of B. platyphylla cuttings overexpressing miR156 was much higher than that of the wild type, and the induced root primordia occurred earlier, indicating that miR156 could promote the adventitious roots of B. platyphylla shoots.