This paper presents a novel cooperative herding strategy with an open-formation configuration called “FlexNet” in pursuit-evasion games under limited field of view. It is first proved that the desired formation of FlexNet can be generated with limited angular field of view. Then a cooperative pursuit strategy with FlexNet is proposed, which can capture a maneuvering evader by adjusting the shape of the formation. Mathematical proof is given on the capture condition of the FlexNet formation under specific dynamics model of the evader. Compare with closed formations, an open formation allows for better flexibility and reduces cost by using fewer pursuers to achieve a successful capture. Simulation results show that the proposed open-formation configuration and the pursuit strategy is capable of accomplishing given capture tasks.