Abstract: This paper addresses the traffic demand analysis problem for the project which has wide incidence and complex road system .A new traffic demand analysis method is proposed by using OD estimation with TransCAD plat-form .By using the background traffic flow as the link flow and setting up virtual partitions ,OD estimation can be carried out .According to the relationship between OD matrix and PA matrix ,the passenger flow of virtual partitions can be ob-tained .Then ,the forecast of virtual partitions and the area can be done by four-stage transport demand forecasting .Fi-nally ,the proposed method is demonstrated by using a traffic demand analysis for the adjustment of the regulatory de-tailed planning of a city as an example ,which proves that the proposed method is reasonable and effective .