This paper mainly focuses on the configuration location designation of variable message sign. The random error term of Probit traffic assignment model stands for the difference between roadway situation and traveler’s expectation and it has an effect on the assignment result. Different assignments result in different roadway network situations. In this paper,the BPR function and HCM2000 signalized intersection delay model are taken to evaluate the roadway network operations and variable message sign locating procedure is also set up. A4×4 roadway network is taken as the numeral sample and the best location of variable message signs are determined. Based on the method mentioned above,the influence of information coverage on the roadway network operations and the influence of information accuracy on the roadway network operations are discussed. The results show that the total expected roadway network travel time tends to decrease with the expansion of information coverage and improve of the information accuracy.