Abstract: 【Objective】Our objective was to understand the functions of the BpMYB4 gene during low-temperature stress.【Method】We performed the following experiments in this study. Firstly, we analyzed the expression pattern of the BpMYB4 gene in different tissues of birch, including roots, stems, leaves, xylem and buds. Secondly, we constructed the plant overexpression vector of PGWB2-BpMYB4, and generated birch transgenic lines that overexpressed BpMYB4 using Agrobacterium-mediated transformation. Then, a polymerase chain reaction(PCR)and quantitative real-time PCR(qRT-PCR)were used to identify the transformants. Finally, we examined eight physiological indexes of transgenic birch under low temperature using spectrophotometry.【Result】Campare with the expression of BpMYB4 in buds, the highest expression level of BpMYB4 was in the veins of the third leaf and the tender stems between the first leaf and the second leaf. We obtained 13 independent 35S::BpMYB4 transgenic lines and PCR results provided preliminary evidence that exogenous BpMYB4 was integrated into the genome of birch. qRT-PCR results indicated that BpMYB4 expression in MYB-8, MYB-11 and MYB-12 lines was significantly higher than that in the non-transgenic birch(NT). Under cool stress, overexpression of the BpMYB4 gene in birch increased enzyme activities of SOD, POD and CAT. Overexpression of BpMYB4 also increased contents of OPC, soluble sugar, soluble protein, and proline. Compared to NT, the content of malondialdehyde(MDA)in transgenic birch was reduced.【Conclusion】The results indicated that BpMYB4 transgenic birch could produce protective substances under cold stress, and it will have an ability to resist cold. It can be developed into a freeze-resistant preferred strain.