With the high development of wireless network and mobile devices, Location-Based Services(LBS) is even more popular. Especially the k Nearest Neighbor (kNN) queries providing the services such as searching for nearby hot spots or high rated restaurants etc. In this paper, we study a special type of kNN query named visible kNN query. The query retrieves data objects that are visible to a user in a given view field. The kind of query is useful in many real-world applications such as environmental surveillance or simulation games. We design an efficient algorithm that can retrieve visible data objects in a view field without scanning all the data objects in the data space. We also conduct experiments to evaluate the efficiency of the proposed algorithm. The experiment results show that the proposed method is efficient.