Traditional stationary wireless sensor networks usually have problems, such as low tracking quality, high energy consumption and so on, during the process of target tracking. More and more mobile elements, i.e., mobile sensors, are used in wireless sensor networks and thus bring new solutions for target tracking. The existing research usually confuses detecting the target with locating the target. After distinguishing between the detection-centric and localization-centric methods, this paper reviews specifically the current research status of the detection-centric target tracking methods. By comparing the merits and demerits of the existing methods in aspects like tracking quality, energy consumption, etc., it reveals their problems. In the end, it summarizes some possible research hotspots and tendency of mobile solutions in many aspects.