The discharge in mixtures of inert gas with sulfur vapors is an effective source of radiation spectrum, which is similar to solar in the wavelength range of 280-600 nm due to strong emission of S-2 molecules (B-3 Sigma -> X-3 Sigma-transition). This phenomenon is utilized in microwave sulfur lamp. Despite a number of advantages microwave sulfur lamps have disadvantages that prevent their widespread use. This paper presents optical properties of the pulsed-periodic discharge in mixtures of argon with sulfur vapour in UV and visible spectral region and a global model of the discharge. Emission of the pulsed-periodic discharge in argon-sulfur vapour mixtures was studied at argon pressure up to 100 Torr and pressure of sulfur saturated vapors determined by temperature of gas-discharge tube walls varied due self-heating from the room temperature up to 160 degrees C. It is shown that strong band of S-2 molecules are observed in the discharge emission in the wavelength range of 300-600 nm and S and Ar lines are predominate in the wavelength range of 600-1000 nm. Effect of the discharge conditions on emission spectra was investigated. Time profiles of plasma species densities under various Ar-S-2 mixture compositions and voltage pulse up to 15 kV with duration similar to 10 mu s were calculated using the global model. It is shown, that densities of S-2* molecules fast increases at the voltage pulse beginning and reach maximum after similar to 2 mu s, so strong radiation of S-2* is characteristic for the time interval, then S-2* density fast decreases.