Abstract: Kangding airport, to be constructed at an elevation of 4232.5 m above sea level, is located on the south-west foot of Zheduo mountain stretching from south-east to north-west on eastern Tibetan Plateau. It will be the second highest airport in the world after Bangda airport (4,400 m) located on Tibet. The Zheduo mountain consists of a granite batholith surrounded by a vast quaternary bajada with a width of 4 to 5 kilometers. The airport is situated on the south-western part of the bajada. The rock debris was transported to the base of the range by landslides and rock falls tend to fully cover the Zheduo granite base rock. Besides boulders, gravels and sands, special boulders with diameters of 30 to 100 cm without the other fine grains exist under the foundation of the airport. Those boulders have a rough surface in either sub-rounded or sub-angular shapes. They are buried within 2 meters of depth and spread in forms of ,stone nests,, ,stone rivers, and ,stone seas,. The special boulder is a product of a long evolutionary process, in which the colluvial deposits were removed by underground erosion. In general, the boulders, gravels, sands and special boulders are good foundation materials. Nonetheless, underground erosion causes settlement and deterioration of engineering properties. The apparent free falling of these special boulders poses potential threats to the stability of the airport foundation. Therefore, drainage is a key component in construction of the foundation to assure its stability.