In this paper we study the influence of the period between U-shaped split-ring resonators (SRRs) on the trans- mission/absorbtion properties and refraction index of metasurfaces in THz frequency range (0.1 - 1 THz) using experiments and numerical simulations. The metasurfaces are formed by U-shaped SRRs arrays. The period varies from 63 to 300 μm The metasurface electromagnetic responses are obtained using terahertz time-domain spectroscopy. The experimental and numerical results reveal the shift in transmission spectra for the metasurface response and the tuning of absorbtion intensity at the period between U-shaped SRRs changing. The notable change in the metasurface refractive index is shown.