Abstract: In this paper, the state of traffic flow is represented by the vehicle particle system, and the traffic flow parameters are expressed based on the centroid parameters of the vehicle particle system in a specific instantaneous section area.The spatio-temporal similarities and differences between the traffic flow parameters expressed based on the centroid parameters of the vehicle particle system and the traditional parameters are analyzed by setting three traffic flow trends and the composition of two types of vehicles on the road segment.The results indicate that the trend of the traffic flow speed vcis the same with the space mean speed the former being represented by the centroid parameters.Moreover, the centroid speed vccan better timely reflect the spatio-temporal synchronous change characteristics of the traffic flow speed and also reflect the impact of vehicle mass (i.e. inertia)and its distribution characteristics on the changing situation of the traffic flow. However, the space-mean has a time lag compared to the centroid speed vc. By comparing the traffic flow density parameters characterized by the two methods, the spatial distribution state is found to be basically consistent.The traditional time-varying process of the traffic flow parameters has a time lag compared with the traffic flow represented by the centroid parameters.