Effects of monosaccharide (glucose and fructose) on the retrogradation of lotus seed starch were studied from the aspects of crystal structure, molecular structure and molecular weight. The results of X-ray diffraction, nuclear magnetic resonance and infrared spectrum showed that glucose and fructose could inhibit the recrystallization of lotus seed starch. The crystallinity, double helix structure and short-range ordered structure decreased, and the proportion of amorphous area increased in the composite system, indicating that glucose and fructose might inhibit the retrogradation of starch. The inhibition of glucose on starch retrogradation was more significant than fructose, which might be related to the enhancement of glucose-water interaction. Gel permeation chromatography analysis showed that the molecular weight Mn and Mw of glucose and lotus seed starch composite system increased significantly when compared with lotus seed starch alone, while the Mn and Mw of fructose system decreased significantly.