A symmetrical π-shaped metaaterial is investigated.Numerical simulations exhibit the negative-refractive property of this structure.The complex refractive index n,wave impedance z,effective permittivity εand effective permeability μ have been retrieved from the simulated S parameters.The negative-refractive band lies between 11.2 GHz and 13.05 GHz.The frequency band with high transmission with low loss occurs between 11.95 GHz and 12.5 GHz.which is helpful for practical applications.The mechanism of the electromagnetic resonance is also revealed.