Abstract: In order to obtain the best condition of hot water extraction of lotus seed polysaccharides, the effects of three single factors ( extraction temperature, extraction time, ratio of water volume to raw material weight ( w/m ratio) ) on the yield of lotus seed polysaccharides were investigated.Based on the data of single factor experiments, the optimal extraction technology of lotus seed polysaccharides was obtained by response surface methodology was as follows.: extraction temperature was 83 ℃, extraction time was 3 h, the ratio of water volume to raw material weight ( w/m) was 30 ∶ 1 m L/g. Under these conditions, the yield of polysaccharides was 8.13% ± 0.04%, which was consistent with the theoretical prediction value ( difference value lower than 1%) .Moreover, the microstructure of lotus seed powder before extraction and after extraction were observed and compared by environmental scanning electron microscopy. The results showed that: the whole cells of lotus seed powder were destroyed after hot-water extraction. The powder was different sizes, and its surface displayed schistose shapes, rough and irregular cracks.The microstructure of lotus seed powder before and after extraction was significantly different.It indicated that the soluble polysaccharides could be extracted greatly from lotus seed powder using the optimized hot water extraction process.