The traditional approach to designing filtering antennas involves conducting numerous simulations, which consumes a significant amount of time and computational resources, demanding a high level of expertise. This paper presents a novel approach to designing filtering antennas using the Grey Wolf Optimizer (GWO). Firstly, a structure with free-form metal patterns is constructed to fulfill the filtering function requirements. Next, the GWO is employed to optimize the parameters of the free-form metal pattern. Finally, the optimized metal pattern is integrated into the final antenna structure. The key to this approach lies in the fitness function enabling the GWO to evaluate the filtering response automatically. This method streamlines and automates the development of filtering antennas, making it possible to design them without prior knowledge of filtering principles. To validate our approach, we applied it to design a filtering magneto-electric dipole (ME-dipole) antenna, demonstrating its effectiveness and reliability.