We discussed the problem in the air-condition air feed-distribution system of X type aircraft. We calculated pressure loss, temperature, flux, and velocity of flow by using hydro-simulation. Then, we compared the air-condition capability test data with the simulation results. After the analysis, we chose the best distributing scales of cockpit and cabin, and finally determined the best improvement scheme of air feed-distribution system.The improved system is freindly to operation and maintenance, and can well meet the performance requirement.