Millions of users a day using location-based social network applications such as Foursquare, Facebook Place, or Google+ to find, share or check-in their locations or point of interest to friends. However, the position may have been disclosed to other people who might not be fully trusted, and those people may be malicious stalkers. To obscure the user location, this paper proposes a novel location sharing approach, GPShare, which uses a grid based structure and key sharing techniques. Our lightweight algorithm is also designed to support a wide range of mobile devices. The experimental results show that GPShare is practical in location-based applications while also minimizes the computation time as well.