In this work, using first-principle calculations based on the density functional theory (DFT), the structural and electronic properties of the ternary compound ZnSnAs$_2$ are presented. An accurate ab-initio plane wave pseudopotential method within meta-generalised gradient approximation (MGGA) has been performed forbulk ZnSnAs$_2$ chalcopyrite semiconductor. Additionally, the modified Becke Roussel exchange potential has also been used to improve the underestimated DFT-calculated band gap. DFT-MGGA computations reveal that ZnSnAs$_2$ chalcopyrite has direct band gaps of 0.66 and 0.67 eV.A proper investigation of the electronic structure of the studied chalcopyrite is helpful for photonic devices.