Regional monitoring is widely used in the fields of traffic management, public safety and military target monitoring, and how to monitoring region under prior information and detect more regions is a necessary question. Most of the existing algorithms receive the target information passively, and do not consider how to track the target actively under the known target position. Considering the above problems, this paper improves the MOPSO algorithm, which is based on the prior position information of the target to ensure the radar coverage of the target and obtain the optimal radar layout under the current radar conditions. When the target position information is known, the Prior information MOPSO(PI-MOPSO) algorithm can obtain a greater degree of radar effective coverage under the condition of stable tracking target. Compared with other algorithm, the PI-MOPSO has better results.