Phosphoglucomutase (PGM) is considered an essential catalyst in polysaccharide biosynthesis, plays a pivotal role in the early stage of carbon metabolism and the synthesis of nucleotide sugars. Polysaccharides are important active components of Sanghuangporus vaninii. Based on the transcriptomic data, the successful cloning and re-annotation of the putative 1353 - bp PGM took place, which encodes a protein of 49.45 kDa. In order to elucidate the function of this gene, overexpression and interference transformation systems were constructed in S. vaninii. The results revealed that the PGM is primarily responsible for regulating the interconversion between glucose-1-phosphate and glucose-6-phosphate. An up - regulation of PGM expression resulted in a significant increase in extracellular polysaccharide content, quantified at 7.72 % and 15.15 %, whereas a down - regulation of PGM expression resulted in a significant increase in intracellular polysaccharide content (33.68 % and 38.24 %). The antioxidant capacity of intracellular polysaccharide in strain, including hydroxyl radical scavenging, superoxide anion radical scavenging, 2-diphenyl-1-picrylhydrazyl (DPPH) scavenging, ABTS