简单介绍了交通流理论的发展概况 ,指出交通流理论在目前有着广阔的发展前景 研究了交通流的流体模型理论 ,从速度 -密度关系出发 ,求得车流密度的一般表达式 由此表达式分析车流密度的变化情况 ,得出车流密度的时空图 同时对有匝道的流体模型理论 ,给出了一种求解流体模型方程的差分格式 ,从而迭代出了车流密度的变化情况 ,也给出了车流密度的时空图 The general situation of traffic flow theory is briefly introduced. It is pointed out that the theory of traffic flow has broad prospects for development at present. The fluid model theory of traffic flow is studied. From the speed-density relationship, the general expression of traffic flow density is derived from the expression The paper also gives a spatio-temporal map of traffic flow density. At the same time, a fluid-model theory with ramp is given, and a difference scheme for solving the fluid model equation is given. The variation of traffic flow density is also iterated, Spatial and temporal graph of density