Abstract: Based on the field data collected from Beijing,Shanghai and Guangzhou city,this study applied regression analysis method to build speed-flow relationship model and furthermore calibrated Greenshields model.Considering results of two aspects synthetically,the ideal capacity of expressway and correctional coefficients of different lanes are recommended.Consequently this study can not only provide reference for the planning,design and operation analysis of expressway,but also help to revise the interrelated code or criterion of urban streets.