Coverage model is often applied in spatial networks to evaluate site planning and robustness of networks. The visualized coverage model is helpful for people to understand and analyze these spatial data, in support for better decision. In this paper, we propose a novel dynamic coverage model for carparks around the city. Every carpark is quantified dynamically by its service capability, which is calculated in real time by the algorithm ParkingRank proposed in our previous work. Then an improved weighted Voronoi diagram featuring boundary constraint is introduced to map the quantified service capability of each carpark to the geospatial space, forming a seamless and non-overlapping coverage over the city. The best advantage of this model is the coverage scope of each carpark will dynamically adjust with its service capability varying, while the seamless and non-overlapping feature of coverage would be kept throughout from the perspective of the whole city. It is the first time that the network of carparks is modeled in a visual way, from which the city-wide parking management will get powerful decision supports in the future.