This research was started by taking soil samples and testing conducted in the laboratory to determine the physical and mechanical properties of the soil, then continued with making soil samples for testing of free compressive strength and CBR Lab. with 5 variations of zeolite from 0%, 10%, 15%, 20% and 25%. From the results of this study, it was found that the soft soil sample had moisture content = 90.58%, bulk weight = 1.52 gr/cm3, specific gravity = 2.26, liquid limit = 65.20% and plastic limit = 36.96% with a plastic index value of = 28.24%. Based on the soil classification system using the USCS (Unified Soil Classification System), the soft soil types from the Bili-bili Dam include CH (Clay-High) soil types, clays with high plasticity values. Free compressive strength test on stabilized soft soil samples with various variations of zeolite obtained the highest compressive strength value of 0.259 kg/cm2, namely the soft soil sample + zeolite = 25%. The soft soil without zeolite has a CBR value of 1.24% and after the addition of zeolite, it has a significant increase, up to 74.10% in the 25% soft soil sample. The results showed that the soft soil of the Bili-bili Dam, which was stabilized with zeolite, could be recommended as a subgrade material for the road.