Abstract: The thesis explains the origin of traffic rules from evolutionary game,and takes straight rule as an example.Firstly,it points out that bounded rational drivers imitate high pay strategy as his action mode,which leads to the proportion of drivers,who takes left ways,may change with time.Then,the proportion of drivers,who takes left ways,is affected by two factors.One factor is the comparison between income of turning left and income of the colony,and the other is prophase's proportion of drivers taking left ways.Finally,by analyzing the model,conclusions are drawn that straight traffic rule is a random matching of repeated game's outcomes in bounded rational participants,and straight traffic rule possess diversity and local stability.