Tetragonal ZnP2 single crystals have been prepared by means of resublimation method. Tile near-normal incidence reflectivity of single-crystal tetragonal ZnP2 have been measured at room temperature for E//C-axis and E⊥C-axis in the wavelength range 3000Å-1.2 μ. More reflectivity structures have been observed. Combining the existing reflectivity data, optical functions (dielectric constants, energy-loss function, and effective number of electrons) have been determined from a Kramers-Kronig analysis in the pnoton energy rarige 1-5 eV. Comparison of experimental results with existing band structure calculation has been made and the most probable direct interband transitions are proposed to interpret the reflectivity structures.