The development of technology related to renewable materials continues to be developed. Composite is one of the new materials that is developed sustainably. Its use begins to be combined with natural fibers which can be updated and biodegradable. One of them is the use of kenaf fiber as a composite material for composites. Hybrid composites are developed to obtain the desired mechanical properties. The addition of silica filler can increase the surface adhesion of the composite so that a strong bond between the matrix and filler is obtained. The aim of the study was to determine the effect of silica volume fraction on the mechanical and physical properties of epoxy / kenaf / silica composites. In this study the kenaf fiber used was raw fiber with chemical treatment. The length of fiber is 5 mm and the comparison of the volume fraction variation of epoxy / kenaf / silica is 70: 28: 2, 70: 27: 3, and 70: 25: 5. Silica particles using 37 μm in size. Composite fabrication was carried out using a single layer random fiber method hotpress molding machine with a measured pressure of 5 MPa at room temperature for 30-50 minutes. The mechanical testing performed is a bending test which refers to the ASTM D790 standard and impact test which refers to the ASTM D6110 standard. The physical test carried out is a water arboreal test which refers to the ASTM D570-98 standard with immersion time of 216 hours and the measurement is carried out at 12-hour intervals. Composite fracture results of the tensile test were characterized using an optical microscope to determine fiber distribution and using scanning electron microscopy (SEM) to determine the microstructure of fault morphology. The results showed the highest impact toughness, bending strength, and modulus of elasticity of bending were composites with a volume fraction of 70: 28: 2 with values of 7.49 kJ / mm², 59,180 MPa and 4,658 GPa, respectively. From the results of water and impact fractures, the addition of 2% silica has a low absorption and good matrix bond when compared with the addition of 3% and 5% silica