By using the plane-wave ultrasoft pseudopotential method within the generalized gradient approximation, the structure parameters, band structure, electronic density of states, magnetic moment, and optical properties of Na+ doped tetrahedral Co(1-x)NaxCr2O4 system are fully investigated. The results indicate that Na+ is easier to enter tetrahedral sites (Co) in comparison with octahedral sites (Cr) with ion doping fraction of 0.125 for Na+. With the increase of ion doping fraction of Na+ in Co(1-x)NaxCr2O4 system, the lattice parameters become larger as in the usual case, on the contrary, the magnetic moment and band gap become smaller. Meanwhile, the Fermi level moves deeper into the valence band region. In addition, the absorption spectra of Co(1-x)NaxCr2O4 shift to red in the low energy region, and a strong absorption in the low energy region is obtained. This indicates that the doping Na+ can substantially improve the absorption of visible light and enhance catalytic efficiency of CoCr2O4.