We performed high-level ab initio calculations on electronic structure of NaK.The potential energy curves (PECs) of 10 Λ-S states correlated with the three lowest dissociation limits have been calculated.On the basis of the calculated PECs,the spectroscopic constants of the bound A-S states are obtained,which are in good agreement with experimental results.The maximum vibrational quantum numbers of the singlet ground state X1Σ+ and the triplet ground state a3Σ+ have been analyzed with the semiclassical scattering theory.Transition properties including transition dipole moments,Franck-Condon factors,and radiative lifetimes have been investigated.The research results indicate that such calculations can provide fairly reliable estimation of parameters for the ultracold alkali diatomic molecular experiment.