高速公路交通流模型是高速公路交通监控系统设计、分析、仿真、运行的基础 .由于高速公路交通流模型是一个高阶非线性时变系统 ,这使得该模型的状态估计问题成为一个非常困难的问题 .这里简要描述了传统解析模型中的交通流宏观动态模型及扩展的卡尔曼滤波法( Extended Kalman Filter- EKF)状态估计原理 ,讨论了该类模型在一条具有三个等长路段 ,一个入口匝道 ,一个出口匝道的公路的应用 ,并利用 EKF得出对三路段高速公路车流密度、车流速度跟踪的仿真结果 .仿真结果表明了算法的实用性 Expressway traffic flow model is the basis of design, analysis, simulation and operation of expressway traffic monitoring system.As expressway traffic flow model is a high-order nonlinear time-varying system, it makes the state estimation problem of this model become a very difficult The paper briefly describes the macro dynamic model of traffic flow and the Extended Kalman Filter (EKF) state estimation theory in the traditional analytical model. It is discussed that a kind of model with three equal length sections, one entrance Ramp and an exit ramp, and the EKF is used to get the simulation results of the traffic density and the speed of the traffic on the three sections of expressway.The simulation results show the practicability of the algorithm