With the development of the airport as the core of urban integrated transportation hub and airport MRT system, the projects of underground structures undercrossing airport are gradually increasing. Taking an airport MRT engineering shield undercrossing aircraft taxiway as the background, some key problems of shield tunneling under the airport are studied. Through the reasonable equivalent calculation of aircraft load, the relationship between the buried depth of shield and the load value of aircraft is determined. Combined with the engineering example, the stress analysis on the shield segment undercrossing the taxiway is carried out and the structural measures are proposed. The influences of the buried depth of the shield and the rate of ground loss on the airport pavement settlement are studied. The relevant measures to control the shield settlement are summarized.