Abstract: PHMPs extraction conditions were optimized by ultrasonic-assisted method from the power of the P. hepiali fermentation mycelium. Then the phenol sulfuric method, Coomassie brilliant blue staining method, Meta-Hydroxydiphenyl, Fourier transform infrared spectroscopy (FT-IR), high performance gel permeation chromatography (HPGPC) and 1-phenyl-3-methyl-5-pyrazolone (PMP) pre-column derivatization method were applied to analyze chemical composition, molecular weight distribution and monosaccharide kinds. Results showed the optimal extraction conditions with an extraction yield of 13.10% ± 0.22% for PHMPs were determined as follows: Extraction temperature 81 ℃, extraction time 36 min, ultrasound power 297 W and ratio of water to raw material 44 mL/g. Furthermore, the chemical composition analysis revealed that the contents of neutral sugar, protein, uronic acid, phosphate were 78.48% ± 2.08%, 9.82% ± 0.09%, 3.76% ± 0.11%, 2.23% ± 0.09%, respectively. The FT-IR spectra showed the several characteristic functional groups absorption of carbohydrate existed in PHMPs. High performance gel permeation chromatography inferred that the PHMPs was composed of two main peaks of 638 and 575 kDa, with a wide molecular weight range of 5.6~285 kDa polysaccharide fractions. The monosaccharide composition tests indicated that there were the main monosaccharides of mannose, glucose and galactose in molar ratios of 42.32:27.58:21.14 and a small amount of ribose, rhamnose, glucuronic acid, galacturonic acid, arabinose in molar ratios of 0.42:2.89:2.25:1.16:2.24 in PHEMPs.