The daily average passenger flow of Beijing West Railway Station is 150,000-180,000, and could reach 400,000 during peak periods. The station receives more than 60 million passengers a year, and most of them are densely populated in the north and south squares.Traditional monitoring equipments cannot effectively cover the whole square because of small field of vision. so it is difficult to calculate the number and density of people in the square and to predict the number of people entering the station.