Overload and over-limited transportation including its governance became a big public problem during the e- conomic transitional period in China.Using the economics method logic,this present paper explains the reasons why the overload and over-limited transportation often happen on the highway and it is very difficult for governance,from the following aspects:the public nature of highway,likelihood of private supply,operation & maintenance,externalities and hard governance of overload and over-limited.Then,according to the principle of how to define market main body with market allocation and organization control,this paper classifies and analyses the related operation system.At last,it constructs a governance mechanism based on ascertaining the relationships between every related operation systems.So as to recognize the problem of overload and over-limited transportation from economics sight,and establish a theory model for lasting and effective governance of the problem.