In recent years, since airspace restrictions and the volume of passenger traffic are increasing, the rate of flight delay is rising rapidly and the contradiction about it is outstanding. Flight delay event not only holds up passengers' time, but also makes the airlines suffer a lot. So a scientific and reasonable guidance is necessary to reduce the delay effect. This paper firstly establishes a method to assess the degree of airport delays and get all factors which caused the flight delays

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... ification, and ultimately we offer a proposal to deal with the flow factor, which is the principal reason for flight delays. Research on reducing flight delays began much earlier in abroad. For example, in the optimization of flight plans, as early as the middle of the last century, how to optimize the flight time has already attracted the attention of the optimization experts of the airline flight plan and they carried out some researches. Mathaisel and Etshmaier [2] summed up internationally renowned scholars for the flight planning research from the 60 s of last century to the mid-80 s. They believed that the airline should use the structural optimization of the flight plan assessment and establishment of flight plan these two means to produce the best flight scheduling which can satisfy the actual demand. And Barnhart C and Corn A [3], the two scholars have made a summary of the research results on existing airline flight scheduling. Researches on time optimization and flight frequency of flight scheduling are also rich in the foreign countries. For example, Wei and Hanse [4] proposed to establish the target planning model to maximize the profitability of the entire route and minimize passenger delay rate. Then it can determine the actual flight frequency and simultaneously carry out market share analysis to optimize the flight running time. In addition, Lohatepanont M and Barnhart C [5] also analyzed the relationship between the airline supply and the passengers demand and put forward the establishment of a comprehensive model optimization flight plan from the aspects of model assignment and route selection, etc. What's more, one of the effective solutions is to implement air traffic flow management. Research on flow control began in 1970s overseas. The traffic management system it used can effectively alleviate the partial traffic jam. In America, the United States Federal Aviation Administration has adopted an enhanced traffic management system. The system played a huge role in the system integration, solutions, monitoring and controlling, expert assessment and easy expansion, etc. In Europe, the central traffic management system was established in 1989 to provide ATFM services for all EU member states. In terms of flow control, foreign scholars also made a lot of researches. For instance, Sherali HD, Bish EK and Zhu X. [6] discussed airline fleet assignment concepts, models, and algorithms. Peter B. Vranas, Dimitris J. Bertsimas, Amedeo R. Odoni [7] and some other scholars [8] [9] [10] [11] [12] studied on the real-time problem of terrestrial waiting strategy and the multi-airport limited ground waiting strategy. In addition, the management of airspace is also one of the hotspots in air traffic management, and especially the collaborative decision-making mechanism has attracted much attention from many experts. The collaborative decision-making mechanism changed the previous centralized control model, and combined with the traditional optimization algorithm to improve the mathematical model. In the meantime, it enabled decentralized management collaborative decision-making model to the process of air traffic management. Initially, it implemented the CDM program in the United States, and used information sharing of air traffic control, airlines and airports three subsystems to achieve the effective resources integration. It has reached the purpose of controlling traffic, and the program has reached a certain effect. S. Ma et al. Compared with foreign countries, domestic research on the problem of flight delays is inadequate. Most researchers paid attention to the flight delay service recovery strategy. They have discussed abundantly on service recovery, governance model and legislation of the flight delay. Although service remediation after flight delays is a solution to flight delays, it's better to develop a more optimized flight plan by harmonizing the relationship among the airport sector, regulators, air traffic control departments, airlines and other aspects, so that it can better control the flow and can effectively solve the problem of flight delays. Scholars did this research. They studied flight Planning and optimization and provided mathematical models. Pita JP, Adler N, and Antunes AP [13], based on