Abstract: Ground-penetrating radar (GPR) plays a crucial role in geological exploration, archaeology, and construction engineering. To improve the detection accuracy of underground targets and enhance imaging resolution, a Vivaldi antenna based on metamaterials with excellent time-domain tailing performance is proposed. By dividing the antenna substrate into five regions and employing different periodic distributions, regions with varying effective dielectric constants are created. This design causes the phase centers at different frequency points to converge, effectively improving the antenna′s time-domain performance. The antenna achieves an impedance bandwidth of 0.40 GHz~4.65 GHz with an S₁₁ < -10 dB and a tailing coefficient of 0.006, which is approximately 11 times lower than that of a conventional Vivaldi antenna, significantly enhancing radar detection accuracy.