The changes of soymilk composition and yuba quality and their correlation in the formation of yuba were studied.The result showed that protein concentration in soymilk increased from 2.80%to 4.35%,soluble solid substances in soymilk increased from 5.10% to 10.0%,protein/soluble solid substances was decreasing,pH value of soymilk decreased from 7.00 to 6.47,amino acids content in soymilk increased from 0.71mg/mL to 2.49mg/mL,reducing sugar in soymilk increased from 0.34mg/mL to1.8mg/mL in the formation of yuba.It was also found that protein content in yuba was decreasing and fat content was increasing,sensory quality,cooking ability and L* increased and then decreased in the formation of yuba.Protein content and fat content were correlated with sensory quality of yuba.L* was significantly positive correlated with color and luster of yuba.Reducing sugar content and amino acids content were significantly negative correlated with the color of yuba,and the correlation coefficient of amino acids was greater than the reducing sugar.