The three existing suburban railways have taken the embryonic form of suburban railways and have played a certain role in the traffic between the suburbs and the main city in Beijing. However，there are still many problems，in the distance between operating stations，service range，operating speed，and bus connections，which restrict the role of suburban railways in regional development. Through analysis，this research puts forward relevant suggestions：First，the function of the city’s sub-center line is positioned as two-way commuter transportation，with a bus-based operation mode，with “Two-way Commuter Trains” stopping and directing at stations. Second，the function of S2 line is positioned as commuting traffic and tourist traffic. Suburban areas are mainly used for commuter transportation functions，and the outer suburbs are mainly used for tourism and sightseeing transportation functions. Third，the function of Huaimi Line is positioned as commuting traffic，tourism traffic and driving development along the line. Fourth，to increase the speed of trains. To electrify the S2 line and the Huai-Mi line，and to extend the urban departure station to Beijing North Railway Station.