Abstract：In the present study, pH，ultrasonic temperature，ultrasonic time and other parameters on protein removal effects of U. lactuca SDF were studied, with the deproteinization rate and the SDF retention rate of U. lactuca SDF were adopted as indexes. L9(34) orthogonal experiment design was adopted to optimize technology parameters of deproteinization of U. lactuca SDF by ultrasound-assisted enzymatic method, to provide the references of studying it’s physiological activities. The results showed：with alkaline proteinase dosage as 1 400 U/g，U. lactuca SDF solution pH as 11.0，ultrasonic temperature as 50℃，ultrasonic time as 1.5 h under the condition of the 0.6% concentration of U. lactuca SDF and ultrasonic power as 200 W, the deproteinization rate of U. lactuca SDF was (83.91 ± 0.18)% and the retention rate of SDF was (86.23 ± 0.25)%. The effect of deproteinization was better than the nine orthogonal experiment groups.