An examination of the process of extracting crude polysaccharides from solely through hot water treatment (HWE) at 60, 80, and 100 °C and through an approach involving high pressure processing (HPP) at 200, 400, and 600 MPa followed by HWE. The physiological properties of the polysaccharides could be explained by the structural analysis performed via FT-IR spectroscopy and NMR spectroscopy, which revealed the extract composition of the protein-bound polysaccharides connected by β-glycosidic bonds. Under the extraction conditions investigated in this current study, the recommended extraction condition was a combination of HPP (600 MPa, 10 min) and HWE (60 °C, 2 h). This condition gave high crude polysaccharide yields (with a 2-12% increase), and β-glucan content (with a 15-20% increase) without disrupting the β-glycosidic bond, as compared to using HWE alone. High pressure extraction could be an alternative technique for reduced extraction temperatures of active compounds from mushrooms.