This study was investigated to research the effects of four small intestinal digestive enzymes and the digestive time of gastric phase and small intestinal phase on in vitro digestibility of phosphorus in plant-origin feeds in order to provide a basis for simulative small intestine fluid composition and optimal digestive time. The experiment was carried out on SDS-Ⅰ bionic digestion system for monogastric animals, and corn, soybean meal and wheat bran were used as trial materials. Experiment 1 included one no-enzyme treatment (control) and four enzyme treatments, which were supplemented with trypsin, trypsin+chymotrypsin, trypsin+chymotrypsin+amylase and trypsin+chymotrypsin+amylase+lipase, respectively. The digestive time of gastric phase was 1.25 h, and the digestive time of small intestinal phase was 4.00 h. Experiment 2: after the small intestinal digestive enzymes were selected,five treatments were made by the digestive time of gastric phase including 0.50, 0.75, 1.00, 1.25 and 1.50 h, respectively, and the digestive time of small intestinal phase was 4.00 h in all of treatments. Experiment 3: after the digestive time of gastric phase was selected, six treatments were made by the digestive time of small intestinal phase including 1.00, 2.00, 3.00, 4.00, 5.00 and 6.00 h, respectively. Each treatment had 3 replicates, and each replicate had 5 digestive tubes. The results showed as follows: 1) trypsin, amylase and lipase could significantly increase the in vitro digestibility of phosphorus in corn, soybean meal and wheat bran (P<0.05). Chymotrypsin could significantly increase the in vitro digestibility of phosphorus in soybean meal and wheat bran (P<0.05), but it significantly decreased the in vitro digestibility of phosphorus in corn (P<0.05). 2) When the digestive time of gastric phase increased from 0.50 to 1.00 h, the in vitro digestibility of phosphorus in corn and soybean meal had no significant change (P>0.05). When the time was up to 1.25 h, the in vitro digestibility of phosphorus in corn and soybean meal was significantly decreased (P<0.05). When the digestive time of gastric phase increased from 0.50 to 1.00 h, the in vitro digestibility of phosphorus in wheat bran was significantly increased (P<0.05), and it had no significant change at 1.25 h (P>0.05). 3) When the digestive time of small intestinal phase increased from 1.00 to 6.00 h, the in vitro digestibility of phosphorus in corn, soybean meal and wheat bran was all significantly increased (P<0.05), and had no significant changes at 3.00, 4.00 and 5.00 h, respectively. It is concluded that 1) trypsin, chymotrypsin, amylase and lipase can be used for simulating small intestinal fluid; 2) the digestive time of gastric phase and small intestinal phase are determined for 1.00 and 5.00 h, respectively.