Location privacy-preserving for location-based service (LBS) in mobile communica-tion networks has been received great attention. Traditional location privacy-preserving methods mostly focus on the researches while users publish the location information to LBS providers. However, it lacks the studies on location privacy-preserving when users acquire location information from location provider (LP). In this paper, we present a K-Anonymous based Anti-positioning Security Strategy (KA-ASS), in order to protect loca-tion privacy during the positioning service phase. Firstly, the anonymous knowledge base (AKB) is built to select the k − 1 dummy location fingerprint for the original positioning request. Then, the Continuous Optimal Fingerprint Selection (COFS) algorithm is proposed to generate the dummy trajectory sequence, which has higher directional similarity and distance similarity with original trajectory sequence. Finally, experimental evaluation on the real-world datasets illustrate that our KA-ASS scheme can not only reduce the anonymous time cost, but also achieve better anonymous quality for location positioning service.