The research of excimer laser has long been a very important aspect of laser science. During the search for a new type of excimer laser medium, we first suggest a NaS system of I-VI column element combination. Because of the low excitation threshold of Na and the energy storage capability of S, the excimer laser system of this combination is expected to have high energy storage and high efficiency tunable characteristics. For experimentally investigating the NaS excimer laser system, we first calculated its potential curves theoretically using the Ab Initio method, and analyzed the results. Some theoretical parameters such as balanced inter- nuclear distance Re, potential well depth De, vibrational frequency spectra (omega) e, transition wavelength (lambda) j, etc., were obtained.