The total flavonoids from blood pummelo peel was prepared by cellulose enzyme hydrolysis, and the extraction yield was measured by coloration method with aluminum nitrate. The effects of parameters including enzyme concentration, pH, hydrolysis temperature and hydrolysis time on extraction yield were investigated by single factor test and orthogonal array design methods. And the notability difference was analyzed with the statistic method of range and variance. The results showed that the optimal conditions were as follows: the enzyme concentration was 5.5%, pH was 5.2, hydrolysis temperature was 52℃, and the hydrolysis time was 50min. The extraction yield of the total flavonoids from blood pummelo peel reached up to 1.52%.