In order to integrate urban developments and improving regional quality, governments usually permit land use rezoning, for example, the industrial areas can be changed to be commercial or resident areas within some limiting factors. While land use rezoning will generate many benefits for developers and citizens, it will also produce serious traffic impacts. Although traffic impact assessment is necessary to land use rezoning, it just can evaluate the impacts under a given development scale, cannot provide the reasonable development scale. For this reason, the development scale can only be determined by the bargaining between developers and governments. So, the primal work from traffic point is to decide the reasonable development scale within reasonable level of service. The purpose of this study is to use the level of service concepts to develop a traffic impact evaluation model and a decision analysis system for determining development scale for land use rezoning. A case study is used to confirm that the proposed methodology is reasonable and effective.