Abstract: This study analyzes causes,characteristics,and main performances of large passenger flow of commuters in rail transit in Beijing.Considering the impacts of large passenger flow on networks,an indicator system is developed to evaluate space distribution of large passenger flow of commuters.Relative Load Factors are defined to describe propagational tendency of large passenger flow of commuters in morning peak hours.Based on operation statistics of rail transit in Beijing,its overall characteristics and temporal-spatial changes are analyzed.Lines,stations and sections which are easily affected by commuters are also identified.Basic rules of scale,directions and temporal-spatial distribution of large passenger flow in morning peak hours are studied.The results show that unbalanced transfer flow has great influences on transfer stations.Location of congested sections are near transfer stations which between suburban lines and urban lines.Lines with more transfer stations have relative shorter time of congestion.