Abstract: Objective:To establish a method for rapid determination of the monosaccharide composition of Ganoderma lucidum polysaccharides by Ultrasonic Assisted Acid Hydrolysis-Ultra Performance Liquid Chromatography-Charged Aerosol Detection(UAH-UPLC-CAD),so as to provide a rapid analytical method for the study of the monosaccharide composition of edible medicinal fungi polysaccharides. Methods:Using Waters ACQUITY UPLC Amide column(3.0 mm×100 mm,1.7 μm),gradient elution(A was 0.8% formic acid solution,B was acetonitrile),flow rate:0.4 mL·min^-1,column temperature:25 ℃,CAD detector:atomizer temperature:35 ℃,N₂ pressure:61.2 Psi. Results:The optimum conditions of ultrasound-assisted acid hydrolysis were obtained:ultrasonic power 270 W,hydrolysis temperature 70 ℃,hydrolysis time 1 h. Under the optimized UPLC-CAD condition,the compounds were separated well and the sensitivity was high,and the method had better precision,reproducibility and stability. Seven monosaccharides(molar ratio∶rhamnose∶fucose∶xylose∶arabinose∶mannose∶glucose∶galactose=5.90∶5.34∶72.64∶31.96∶1.00∶1.89∶5.24)in the acidolysis products of ganoderma lucidum were determined by this method. The contents of mannose and glucose were lower,with values of 0.45±0.01 and 0.85±0.04 mg/g,respectively. Conclusion:This method is simple,rapid and sensitive,which provides method support for the study of monosaccharide composition of medical fungi polysaccharides.