Abstract: In order to decide the construction scale of railways and routine buses,distribute the traffic volume reasonably by adjusting the fare policy,the effects of fare on traffic structure is studied in this paper.Questionnaire investigations of public traffic mode split were done in Beijing.Influencing factors of selecting railways and buses are analyzed.The results show that trip time,cost,sex,age,occupation,income,and trip intention have marked influences on the results of trip mode split.On the basis of combination of variable factors,the variables that should be used in the model were determined and the model of public traffic mode split based on disaggregate model is given in this paper.The relationship between fare and mode split is studied, which provided a base for adjusting the structure of public traffic by using the fare policy.