For the enhancement of enzyme activity, application of ultrasound irradiation on lipase-catalyzed esterification of fructose with palmitic acid in ionic liquids (ILs) mixture containing supersaturated fructose solution was investigated. In the mixture of [Bmim][TfO] and [Omim][$Tf_2N$] (1:1, v/v), 1.44 times higher enzyme activity (29.2 ${mu}moL/min/g$) was achieved under ultrasound irradiation. Besides, ultrasound irradiation enhanced enzyme stability in viscous ILs mixture. After 5 times reuse of Novozym 435 and ILs mixture, 84.4% of initial enzyme activity was remained under ultrasound irradiation, while the residual activity using magnetic stirring only method was 76.2%. These results show that enzymatic reaction in viscous ILs mixture under ultrasound irradiation is an effective method for enzyme activity, as well as, enzyme stability resulting in economic competitiveness of green process.