Conventional basin-type solar still (CSS) is the simplest type of solar water distillation system. In this study, CSS was modeled and simulated. The effect of variations in water mass inside the basin, absorber absorptivity, glass absorptivity, glass reflectivity and heat loss coefficient were investigated. Finally, the system was simulated using the same data of solar radiation intensity, ambient temperature and wind speed in each variation and the highest distilled water results are 2.33 kg in water mass inside the basin variation of 5 kg, absorber absorptivity variation of 0.9, glass absorptivity variation of 0.06, glass reflectivity variation of 0.08 and heat loss coefficient variation of 14 W/(m2.K). Overall study shows that TRNSYS is a very useful tool for design and parameter analysis of solar water distillation system.