A method for estimating road travel time based on the built environment and low-frequency floating car data belongs to the technical field of urban traffic management and traffic system evaluation. The method takes built environment as an explanatory variable of the road travel time. The interpretability of this variable is proved by a numerical example. In addition, the method determines distribution parameters of road travel time using the number distribution of vehicles instead of distance. The benefits of the method are that: (1) it explains the positive effect of built environment on road travel time; and (2) it reflects the speed difference among different road sections, which can improve the precision of estimating road travel time.