According to the travel time estimation problems in the urban road traffic flow, two travel time estimation models are presented in this paper. The velocity model is based on the average velocity of vehicles at the adjacent monitoring points, and the retention time model is based on the free driving time and the residence time used in road between two adjacent monitoring points. The models are validated by the traffic data collected on an urban road in San Antonio, USA. With the further analysis on the results of the two models, the applicable conditions and influencing factors are given for the two models respectively.