This study aims to investigate the structural characteristics and anti-inflammatory activity of neutral homogeneous polysaccharides isolated and purified from Prinsepia utilis Royle oil meal. The crude polysaccharides from P. utilis oil meal were extracted by water extraction and alcohol precipitation, followed by purification using DEAE-52 cellulose anion exchange chromatography and Sephadex G100 gel filtration chromatography to obtain P. utilis oil meal polysaccharides-A1 (PURP-A1), which was a homogeneous polysaccharide. The structural features of PURP-A1, including its relative molecular weight, monosaccharide composition, characteristic functional groups, glycosidic bond types, and linkage patterns, were analyzed using spectroscopic techniques such as high-performance gel permeation chromatography, ion chromatography, fourier transform infrared spectroscopy, gas chromatography-mass spectrometry, and nuclear magnetic resonance. The anti-inflammatory activities were evaluated using a substance P-induced immortalized human keratinocyte cells (HaCaT) inflammation model. The results showed that PURP-A1 exhibited a relative molecular weight of 18 373 Da, with the main chain polymerized by glucose residues and a branch chain polymerized by arabinose, which were connected to α-glycosidic bonds. At concentrations of 500 and 1 000 μg/mL, PURP-A1 significantly downregulated the mRNA expression of inflammatory cytokines tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), IL-8 and interferon-γ (IFN-γ) in substance P-induced HaCaT cells, demonstrating its therapeutic potential for neurogenic inflammatory skin diseases, providing an important scientific basis for the in-depth development and scientific application of this plant resource in the field of skin health.