From some previous research on expansive soil improvement, can be repaired using cement and rice husk. This study aims to determine the effect of mixing of rice husk ash, cement, alum, and fly ash to the index properties, bearing capacity, expansive soil swell and shrinkage. Expansive soil bearing capacity testing performed by the CBR test, unconfined, UU Triaxial, UU Direct Shear, Free Swelling and in accordance to ASTM. However, there has been no previous studies of cement, rice husk ash, alum, and fly ash levels are optimum, the objective of this study was to find optimum levels. Fly ash generally improve the soil shear parameters with the composition of 6%, 10%, and 15% of the weight of the soil. Rice husk ash is very good to reduce the swelling potential value of 13-30% by weight of soil. Soil bearing capacity obtained good results in a mixture of 14% rice husk ash with 2% cement. Obtained from this mixtures optimum experimental level is 14% rice husk ash with cement 2%, this resulted in improved soil shear parameters, reduce swelling potential, and increase the bearing capacity of the soil.