In order to increase the yield of sea buckthorn leaves flavonoid aglycones converted from flavonoid glycosides by the enzyme-Pectinex Ultra SP-L, on the basis of single-factor test, response surface analysis method was used. Hydrolysis time, hydrolysis temperature and pH value were chosen to be independent variables. The value of flavonoid aglycones quality was regarded as the response value. The results showed that the hydrolysis time was a significant effect factor and hydrolysis temperature and pH value had no significant impact. The optimum conditions for enzymatic conversion were hydrolysis temperature of 50.8℃, pH value of 5.16, hydrolysis time of 2.5h. Under those conditions, the total aglycones quality obtained from 15mg sea buckthorn leaf extract was 0.1801mg and the conversion rate to flavonoids aglycones was 62%.