Abstract: Based on the analysis of the state of driving and service level which was under different traffic regulation of mutilane, the limitation and the adaptability of AADT calculation model which was traditionally applied in China were concluded. The new calculation model about AADT was introduced. All parameters of the new model were discussed in detail. At last, the result which was applied the new model into Nanjing-Shanghai Expressway widening projection was compared with the original one, it was found that the new result had more prominent accuracy than old one.