In order to study the passenger traffic characteristics of check -in hall of airport terminal building, based on the actual situation of check-in hall of Terminal 2 in Nanjing Lukou Airport , this study divides the check-in hall into three areas of the entrance and exit area, the corridor area and the commercial area. The data of three parameters (flow, density and speed) of passenger traffic characteristics in each area collected by video recording method are analyzed, and then the relationship between three parameters is fit by function. The results show that the average speed of passengers in each area of the check-in hall is 0.801 , 1.089 and 1.188 , which are lower than the average speed of domestic and foreign passengers; the fitting relationship between passenger density and speed in each area is inversely linear, and the passenger speed decreases gradually with the increase of density; the fitting relationship between passenger density and flow is a quadratic parabola, and the passenger flow increases with the increase of density, first increases to the optimum passenger flow and then decreases until it reaches the blocking density. The results provide a basis for the airport to establish passenger flow early warning level and further plan and develop the commercial area.