Analysis of slope stability focus, on determining the value of the safety factor (Fs) which is mean the ratio between the shear strength of the soil to the developed shear stress on a certain slip surface. Engineers are interested with the minimum value of FS which is obtained by analyzing some trials of slip surface. In the present work, slope of two cohesive layers of the same unit weight is studying. About (100) different problems are analyzed using the package (Slide 6.0). These problems takes into account the impact of some factors on the minimum value of FS. These factors are: the ratio between the cohesion of the top layer to that of the second one (cu1/cu2) which is denoted by (Cr), the ratio between the height of the top layer to that of the slope (H1/H) which is denoted by (Hr) and the angle of the slope (B). The results of the analysis are normalized as a stability number (Ns).A regression analysis then conducted to these problems using well known package (STATISTICA). The accuracy of the suggested model is tested by R2. The value of R2 of model to predict stability number is about 0.982.