Abstract: The transmural fluxes of L-Leucine and L-Tyrosine were measured by in the intestinal gut, using the in vitro perfusiontechnique. The transmural rates of L-Leucine are01026, 01062 and 01038 (L mol/g/min)when the concentrations of the perfusionLeucine are 110, 510 and 1010mmol/L at the 10 min respectively. The transmural rates of L-Tyrosine are 01006, 01024 and01039 (Lmol/g/min) when the concentrations of the perfusion L-Tyrosine are 015, 115 and 215mmol/L the 10min respective-ly1The total absorption ratios of the L-Leucine are 12.83%, 18.85% and 16.45% when the concentrations of the perfusionL-Leucine are 110, 510 and 1010mmol/L for 40 minutes respectively. The total absorption ratios of the L-Tyrosine are 22.18%,23.68% and 27.49% when the concentrations of the perfusion L-Tyrosine are 0.5,1.5 and 2.5mmol/L for 40 minutes respec-tively.The percentage of the transmural fluxes through the intestinal gut, the free in intestine, that in new synthesized protein andthe remainders in intestine to the total absorbed amino acid were calculated respectively. When the concentration of the perfusionL-Leucine are changed from 1.0mmol/L to 5.0mmol/L and 10.0mmol/L, the transmural ratio are 83%,66% and 35% respec-tively. The free in intestine are 9%,28% and 49% respectively. That in protein are 2%, 5% and 13%. The remainders are6%,1% and 3% respectively. When the concentration of the perfusion L-Tyrosine are changed from 0.5mmol/L to 1.5mmol/Land 2.5mmol/L, the transmural ratio are 52%, 55% and 55% respectively. The free in intestine are 7%, 10% and 16% re-spectively. That in protein are 17%, 15% and 16%. The remainders are 24%, 20% and 13% respectively.