In China's Hainan Free Trade Port, the apron of Haikou's one-stop aircraft maintenance base is crowded with aircraft from global airlines such as Qatar, Vietnam, and Thailand. The maintenance schedule for the next three years is full, and the average annual maintenance volume is as high as 700 sorties. Overseas airlines enjoy preferential treatment in Hainan such as exemption from payment of deposit for inbound maintenance, bonded maintenance of aviation materials, and refilling of bonded aviation fuel. After the superimposed customs closure, the number of "zero-tariff" tax items has been expanded to 6,600, and comprehensive maintenance costs have been reduced by 10%-15%. The aviation materials bonded warehouse realizes "goods waiting for people", shortening the waiting period for parts by 2-3 months; 24-hour customs clearance and "one-stop" services， have compressed the maintenance cycle to the world's leading level