The invention provides a flow-speed matching model and a travel time forecasting method and system. The method includes the steps of firstly, calculating theoretical travel time and traffic flow average speed of a road section; secondly, calculating the error between the theoretical travel time and actually-measured travel time, conducting feeding and adjusting on the traffic flow average speed according to the error, and renewing flow-speed data of the corresponding road section; thirdly, repeating the first step and the second step till the error is smaller than a preset threshold value, and storing the errors as a flow-speed matching model; fourthly, directly conducting matching in the flow-speed matching model through forecasted flow to obtain the average speed, and then calculating the travel time according to the average speed. According to the flow-speed matching model and the travel time forecasting method and system, the travel time is calculated according to the traffic wave principle, feeding and adjusting are conducted on the average speed, the calculation result is corrected unceasingly, and the flow-speed matching model is renewed; the travel time forecasting method is simple, and meanwhile the flow-speed matching model can be enriched and optimized in the travel time forecasting process so that the forecasting model can be higher in accuracy.