Generally, the flocking algorithms with informed agents lead to the generations of the quasi α-lattice which are not so desired as the α-lattices in formation control of multi-agent systems (MASs). Therefore, a flocking algorithm is proposed to form an α-lattice with informed agents in this paper. Under the control of the designed algorithm, the informed agents are connecting to the virtual leader dynamically, which is the key of forming the α-lattice. More precisely, if there are other informed agents closer to the virtual leader in certain informed agent’s neighborhood, the connection between it and the virtual leader will be cut off. The effectiveness of the proposed algorithm for forming an α-lattice is comprehensive proved and validated by several numerical simulations.