In order to investigate the structural characterisation and in vitro antioxidant and hypoglycemic activities of yam leaf polysaccharides and their phosphorylated derivatives, in this paper, yam leaf polysaccharides (Dioscorea opposita Thunb. leaf polysaccharides, DOLP) were extracted by hot-water leaching method, and three phosphorylated polysaccharide derivatives (DOLP-P1, DOLP-P2, and DOLP-P3) with different phosphate content were prepared by the phosphate method were prepared by the phosphate method, and their structures were characterised and their in vitro antioxidant and hypoglycemic activities were investigated using modern spectroscopic and chromatographic methods. The results showed that DOLP and its phosphorylated derivatives were mainly composed of fucose, rhamnose, xylose, galactose and glucose and possessed a triple helix structure. The IR spectra showed characteristic absorption peaks of P=O and P-O-C phosphorylation at 1 066 cm^-1 versus 916 cm^-1, confirming the success of the phosphorylation modification. The crystallinity of DOLP was reduced and the surface morphology changed significantly after phosphorylation modification. The results of in vitro antioxidant and hypoglycaemic activity experiments showed that the phosphorylated Dioscorea opposita Thunb. leaf polysaccharides possessed good bioactivity, and the in vitro antioxidant and hypoglycaemic abilities were as follows: DOLP-P1 > DOLP-P2 > DOLP-P3 > DOLP. Among them, the half maximal inhibitory concentration (IC₅₀) of DOLP-P1 on DPPH, hydroxyl and ABTS radicals were 0.410 3, 1.132, 1.620 mg/mL, respectively; the IC₅₀ on α-amylase, α-glucosidase were 3.990, 1.026 mg/mL for α-amylase and α-glucosidase, respectively. It was shown that phosphorylation modification could enhance the in vitro antioxidant activity and hypoglycaemic activity of Dioscorea opposita Thunb. leaf polysaccharides.