This experiment was conducted to compare the difference between (NH₄)₂SO₄-dialysis-freeze dried-defat (ADFDD) method used and concentration-dialysis-freeze dried-defat (CDFDD) method to purify the digestive enzymes of jejunal fluid of ducks. A two-sample completely randomized design was adopted. Eight liters of duck jejunal fluid were divided into 2 groups with 4 replicates per group, and each replicate contained 1 L jejunal fluid. The 2 groups of jejunal fluid were randomly selected to be treated with (NH₄)₂SO₄-dialysis-freeze dried (ADFD) method or concentration-dialysis-freeze dried (CDFD) method to prepare the digestive enzyme dry powder. Then, the methods of ADFDD and CDFDD were established by defatting the dry powder, respectively. The activities and recovery rates of digestive enzymes, total protein concentration and chemical composition content of digestive enzymes dry power prepared by the methods of ADFD and CDFD, or the methods of ADFDD and CDFDD were compared. The results showed as follows: 1) the activities of amylase, trypsin and chymotrypsin of dry power prepared by CDFD method were 34.8%, 27.9%, and 12.1%, which were significantly greater than those of dry power prepared by ADFD method (P<0.05), respectively; the recovery rates of amylase, trypsin, chymotrypsin and total protein by CDFD method were 34.8%, 35.2%, 15.3% and 12.6%, which were significantly greater than those by ADFD method (P<0.05); the concentrations of crude protein and crude ash in dry power prepared by CDFD method were significantly lower than those of dry power prepared by ADFD method (P<0.05), but no significant difference was observed in the concentration of ether extract (P>0.05). 2) After ethanol defatted, the activities of amylase and trypsin of dry power prepared by CDFDD method were 11.5% and 7.9%, which were significantly greater than those of dry power purified by ADFDD method (P<0.05), but no significant difference was observed in the chymotrypsin activity (P>0.05); the recovery rates and the activities of amylase and trypsin in CDFDD method were 39.4% and 43.9%, which were greater than those by ADFDD method(P<0.05), but no significant difference was observed in the recovery rate of the chymotrypsin activity (P>0.05); the recovery rate of total protein by CDFDD method was significantly greater than that by ADFDD method (P<0.05), but no significant difference was observed in the concentration of total protein in dry power prepared by these two methods (P>0.05); the concentrations of crude protein and crude ash in dry power prepared by CDFDD method were significantly lower than those in dry power prepared by ADFDD method (P<0.05), but no significant difference was observed in the concentration of ether extract (P>0.05). From the entire purification process, the activities of amylase and trypsin and their recovery rates by dry power purified by CDFDD method are greater than those of ADFDD method.