Abstract：Jiuzai—Huanglong airport is located on the eastward slope of Zhangla basin in Songpan County in the northwest of Sichuan. By using FLAC3D program to simulate real construction process，the settlement of the high fill foundation especially differential settlement，which has the most powerful influence on Jiuzai-Huanglong airport is quantitatively analyzed and evaluated. The results indicate：(1) The calculation results coincide with the monitoring results. (2) The settlement center lies in the place of slope shoulder with the maximum settlement amounting to 2.8 m；and the settlement gradually decreases on the runway and the base of slope. (3) The total after-construction settlements have close relations with thickness of the fill and soft layer，i.e. the bigger settlement often presents at the places with thicker fill or thicker fill and soft layer.
