Slope stability issue becomes one of the main problems in construction
industry due to nature of the topography and the weather conditions in  Malaysia. Various of technique can be applied for slope strengthening. One of the effectiveness and economic system is application of soil nail in slope surface. The objectives of the study were; i) to determine the effect of shear strength parameters and groundwater table on slope stability,ii) to determine  the effect of soil nailing on slope stability, iii) to determine the optimum angle of nail inclination and slope degree with higher FOS, iv) to install/apply soil  nail for slope stability improvement in the case study. Various simulation modeling and various parametric study were applied in this study such as slope angles, Ø cohesion, c internal angle of  friction, ф and groundwater level. Then, various inclinations of soil nailing were applied in order to find optimum angle of soil nailing for strengthening slopes. Slope/W software was  used in the slope stability analysis. All the results then were tabulated and recorded in the report. Based on the analysis, it shows that the shear strength parameters affect the stability of slopes by given a highest factor of  safety. Soil nailing also will enhance the stability of slope by increasing in factor of safety. The soil nailing would produce highest factor safety when
an optimum inclination angle of nails is applied.