A new chiral structure working in microwave and optical frequency bands based on folded-wire is designed and simulated. Effective parameters of this structure, including polarization azimuth rotation angle, ellipticity angle, relative permittivity, relative permeability, chiral parameter and refractive index are obtained from simulated transmission and reflection spectra. The results show that the exceptionally strong polarization azimuth rotation angle and the ellipticity angle are found in microwave and optical frequency bands. Because this structure has a large chiral parameter, negative refractive index of a circularly polarized wave can be obtained without requiring permittivity and permeability to be negative simultaneously.