We investigated the optimal extraction condition of Ganoderma lucidum( G. lucidum) fruiting bodies polysaccharides by comparing the four extraction methods of ultrasonic-assisted extraction,microwave-assisted extraction,accelerated solvent extraction and water bath reflux extraction. The simultaneously molecular weight distribution of polysaccharides extracted under different extraction conditions were analyzed by high performance size exclusion chromatography. Results showed that the yield of polysaccharides extracted under ultrasonic assisted condition was higher,and the structure of polysaccharides was less damaged. Moreover,molecular weight distributions of polysaccharides from different G. lucidum fruiting bodies by ultrasonic-assisted extraction were determined and compared.The results showed that the differences were obvious,and the strains,cultivation and geographical regions all had influences on molecular weight distribution.