Abstract:Researchpurposes: With theexpansion of network scale and constant growth of transfer passengers，the requirement of urban transit ’ s operation is ever increasing. Under the condition of limited rail transit resource，it ’ s a key method to use collinear operating mode to realize resource sharingand satisfy thetrip demand of passengers. According to the operation scheme in collinear operation mode，witli the comprehensive consideration of train ’ s carrying capacity， section carrying capacity， number of trains， loading percentage of trains and otiier constraints， this paper started from the point of collinear operation mode ’ s features，concentrated on the operation scheme which can not only meet the trip demand of passengers，bus also can minimize the operating cost of rail transit，so as to maximize the social and economic benefits. Research conclusions ：( 1 ) Y - shaped route is the most common form in collinear operation mode， which can be divided into three kinds by network topology. Each mode has its own advantages and disadvantages as well as adaptability，and they ’ re all influenced remarkably by passenger flow，turn - back line and train formation. (2) In the optimization of Y - shaped collinear operation organization scheme，different capacity of stations and routes，especially the turn - back capacity of turn - back station should be taken into consideration integratedly. According to the change characteristics of passenger flow，a corresponding time scheme should be selected and a rational route system should be made$besides$ single rail lines should be optimized individually. (3) Both the operating cost and the time cost of passengers should be considered in the operating scheme of trains to minimize the total cost. (4) The nesting of trunk line and branches can decrease the total cost effectively. (5) This paper can be applied in the optimization of the operation scheme of urban rail transit.