Abstract: Because of the large cube，low speed of the large-scale passenger cars，the impact of the passenger cars must be considered when the cellular automaton model is created.Based on the overall analysis of the existing classical cellular automaton model of the traffic flow，combined the characters of the freeway in our country，the length of the cellular，running speed，random slow mechanism and lane change are demarcated，and mixed multi-speed vehicles on two-lane cellular automaton model under the impact of the passenger car with period boundary condition is constructed.And the relationship between the speed，density and traffic capacity is analyzed by the computer simulation.The influence rules of the factors of the traffic flow of the method are found out，such as the proportion of large-scale passenger cars，random slow rate，the number of the lane change and so on.The theoretical foundation for reasonable to organize the freeway traffic administration is offered.