To investigate the expression and regulation mechanism of MYB in Lonicera fulvotomentosa under mineral element stress. The MYB transcription factor LfMYB of pioneer plant L. fulvotomentosa under karst landforms was isolated and identified by a combination of transcriptome sequencing and RACE cloning. Prokaryotic expression activity detection and transcription activity verification of LfMYB were carried out. The changes on the content of B element in different organs of L. fulvotomentosa were detected under different concentrations (0, 0.25, 1.0, 2.5 mg/L) of boron (B). The expression characteristics of LfMYB were analyzed by qRTPCR. The expression pattern of LfMYB was analyzed by the treatment of different concentrations (0, 0.25, 1.0 and 2.5 mg/L) of B element and qPCR analysis. The results showed: (1) LfMYB is a transcriptional activator belongs to the R2R3 MYB transcription factor family. (2) The prokaryotic expression results showed that the pCOLDLfMYB recombinant protein could be expressed after different concentrations (0.2, 0.4, 0.8 mg/L) of IPTG induction and the size of the recombinant protein is about 75 KD. The transcription experiments showed that the LfMYB protein can be transcribed and translated correctly in yeast, and LfMYB can activate transcription reporter gene. All these proved that LfMYB has selfactivating activity. (3) The results of qPCR analysis showed the expression of LfMYB in old leaves, white flowers, and yellow flowers was significantly higher than that in other parts, while the expression in young stems and young leaves was relatively low. (4) In karst soil, the B accumulated in the old leaves and stems of L. fulvotomentosa. When a certain concentration of B was applied to the karst soil, the B content in all organs of L. fulvotomentosa increased as the concentration of applied B increased, and the content of B in young stems and green buds increased most obviously, which reached a significant level (P <0.05). The expression of LfMYB increased in all organs of L. fulvotomentosa as the concentration of applied B increased. When the exogenous B concentration is 2.5 mg/L, the expression of LfMYB in all organs of L. fulvotomentosa decreased, among which the expression of LfMYB in young leaves, young stems and green buds decreased most obviously, which reached a significant level (P <0.05). This study provides an experimental basis for revealing the molecular mechanism of B tolerance in L. fulvotomentosa.