Four different pre-treatment methods including ultrasound （US）， ultrasound assisted enzymatic method （US+EM）， ultrasound assisted alkaline method （US+AM）， and ultrasound assisted hot-water method （US+WM） were used to study the effects of different desugaring pretreatment on the quality of red jujube crisps dried with hot air drying and instant controlled pressure drop.The color， texture， taste， and the content of main nutrients in the dried red jujube crisps were analyzed.The results showed that different ultrasound assisted desugaring pretreatment had a significant impact on the quality of red jujube crisps dried with hot air drying and instant controlled pressure drop.Compared with different desugaring pretreatment， the solid reduction rate of fresh jujube samples treated with US and US+EM was 2.53% and 3.36%， significantly lower than that with US+AM and US+WM.The content of polysaccharide in US+WM was the lowest with the best effect of desugaring， followed by US+EM treatment with hot air drying and instant controlled pressure drop of red jujube crisps.The US+EM with instant controlled pressure drop of red jujube crisps resulted in a high retention rate of flavonoid and the smallest loss of VC content.The results of electronic tongue showed that the taste of red jujube crisps pretreated with US+EM and dried with instant controlled pressure drop was best.It is indicated that ultrasound assisted enzymatic （US+EM） treatment reduces the content of sugar while retain the flavor and nutrients of red jujube crisps to the greatest extent.