As the dramatic development of the electronic technology, many of the traditional radar system has been threaten in the modern war. Therefore, we need new technology to overcome all these kinds of problems. The phase array radar is a good solution to all these problems. The phase array radar is constructed of many antenna elements and each antenna element has its own phase shifter. However, the phase array always have a huge amount of money spent on the hardware. This is because each antenna has its own receive path. In order to reduce the hardware cost, we propose a novel algorithm to divide the phase array into the sub arrays. In addition, in order to make the operation be easier, the antenna elements of the sub array should be relatively centered. The simulation results shows our proposed algorithm works well.