Taking the old urban area of Dongyang City as an example, the general process of analyzing the traffic operation state at the congestion points by applying Map API technology is proposed. Firstly, the real-time road condition maps of the research area are captured respectively at certain time intervals, and the congestion points of road are identified according to the road condition color and duration. Secondly, the research scope is divided into a certain number of grids, and the map API technology is used to obtain the estimated travel time from the center of each grid to the congestion point in batches, which can evaluate the accessibility of congestion points at the current time. Finally, the average travel speeds of the roads around the congestion points in each period are obtained to evaluate the time variation characteristics of the road operation state. The map API is used to identify the rod congestion points and analyze the operation state, which can greatly reduce the preliminary workload of researchers, and provide the relatively accurate basic data for the subsequent research and analysis.