In recent years, the rapid development of wireless communication technology has promoted the development of locationbased services (LBS), among which the point-of-interest (POI) query is one of the most important applications. A novel privacy preserving method of k-anonymous model is proposed to solve the problem of leaking location privacy during the query process in road network environment. First, the anonymous server uses the set of points of interest to construct the network Voronoi diagram. Then, the whole road network is divided into independent units which are called network Voronoi cell (NVC) without overlapping. Moreover, the anonymous server uses the Hilbert curve to traverse the road network space and sort the points of interest in accordance with Hilbert order. When a user requests a query, the anonymous algorithm selects dispersed k-1 NVCs which have the same query frequency with the NVC that user located in, and then generates dummy locations in the relative road segments corresponding to the user's in each NVC. The reciprocity of the anonymity set can be ensured and the inference attack that traditional k-anonymity can't resist can be avoided through the proposed anonymous algorithm. Finally, the theoretical analysis and experimental results show that the proposed privacy preserving scheme can effectively protect the location privacy.