In this chapter, we first consider the fundamental fencing problem for a constant-speed target under time-varying topologies. Although some previous works have addressed the fencing control of a constant-speed target, they are limited to solutions based on fixed topology or switching connected topologies, which are only effective in open and unobstructed environments. However, in increasingly complex and dynamically changing environments, it is important to further delve into the collaborative fencing theory and strategies for general time-varying topology, as well as the formation evolution during the fencing process. Therefore, this chapter proposes a distributed cooperative fencing controller via neighboring angle repulsion, which aims at solving the fencing problem of a constant-speed target under time-varying topologies İn what follows, we will introduce the related background.