A mathematical model for investigating warm performance of the ventured sunlight based still which is not performed in most of the previous studies. is developed in this study. Based on the proposed model, a computer program (using Pascal language) is carried out. A stepped solar still consists of five small steps(0.002 m depth, 0.2 m width and 1.0 m length). The effect of configuration parameters on the stepped productivity and efficiency such as the still width (b_s), depth of water (d_w), tray width (W) and the height of tray (H) is considered. Comparing thermal performance of the stepped solar still with that of the conventional one shows that the stepped solar still is more efficient. Correlations of the got results with those introduced in the past investigations have been done, prompt an approving the proposed mathematical model. The outcomes show that, the every day productivities for the traditional and ventured sun based stills are discovered to be 4.0 and 4.51 (kg/m2day); separately. The Daily productivity of the regular and ventured sunlight based stills are 61.48% and 81.85%, individually.