Abstract: Equity of departure flights is an important measurement of sustainable operations in civil aviation.However studies on it are relatively rare compared with flight efficiency.In order to more intuitively measure the degree of difference in delays of departure flights, taking equity value of departure flights of different airliners as object, the concept of equity of departure flights is defined.On this basis, combined with a normalization algorithm, a normalization index is established to evaluate equity level of departure flights.The four main departure directions of Beijing Capital International Airport are taken as a case study to analyze the equity value of departure flights of different airliners.The results show that equity values of four directions obey Normal distribution.The greater the equity value is, the worse the stability becomes.Field investigation verifies that the equity value calculated by the index conforms with practical operations, which means practical.