Abstract: It is difficult to carry out a wide range of origin-destination (OD)surveys for vehicles.The regional OD matrix is commonly estimated by traffic flow in road sections.Considering the fact that the distribution structure cannot be verified through traditional OD estimation methods,a new method is proposed.This method updates the regional OD matrices with a Select Link analysis and replaces them with “real”OD matrices.Firstly,a specific sectional OD matrix computed by Select Link is subtracted from the regional priori OD matrix;then a “real”matrix of this road section is used to update the distribution of regional traffic flow.A two-step iterative replacement procedure is applied when there are multiple road sections in the regional priori OD matrix whose OD matrices need to be replaced by the “real”ones.The first step is to replace each sectional OD matrix one by one.One replaced matrix will be used as input for the next link. The second step is to replace the whole regional priori OD matrix based on the first step.A case study of Guilin Ring (East)highway has been conducted to verify this method.Compared with the traditional OD estimation methods,this new method resulted in an increase of 7% of the long-distance travels,which can reflect the variation of regional distribu tion of vehicles .The correlation coefficient between the assigned and the surveyed traffic flow of road sections reaches 0.99,which verifies the accuracy of the updated regional OD matrix.