Abstract:To determine the effect of wall breaking on the content，structure and monosaccharide composition of crude polysaccharides from Ganoderma lucidum spore，the extraction process of crude polysaccharides was optimized with the extraction content of crude polysaccharides as index. The optimum process parameters for the ultrasonic assistant extraction of crude polysaccharides from G. lucidum spore were obtained as follows：ultrasound temperature 55 ℃and ultrasound time 8 h. Under these conditions，the content of crude polysaccharides extracted from wall-broken G. lucidum spore powders was（15.873±0.746）mg/g.With crude polysaccharides from G. lucidum spore before and after wall breaking that were extracted under the optimum extraction conditions as research object，their content，purity，DPPH free radical scavenging，structure，as well as monosaccharide composition were compared. The results showed that crude polysaccharides from G. lucidum spore after wall breaking treatment increased by 233.396%，but its purity decreased by 19.898%. The scavenging ability of crude polysaccharides against DPPH free radical was also greatly improved after wall breaking.Additionally，wall breaking treatment did not cause significant changes in monosaccharide composition of polysaccharides from G. lucidum spore，but there were marked differences in monosaccharide content，especially fucose，galactose and mannose.The infrared spectrum revealed no significant difference in the structure and composition of crude polysaccharides from G.lucidum spore before and after wall breaking，and they were polysaccharides containing D-pyranose ring.