Nanocellulose is one of the nanomaterials that has developed very rapidly in research and industrial applications over the last decade. The nanocellulose used in this research has a crystal length of 100-150 nm, a crystal diameter of 9-14 nm. Synthesis of barium hexaferrite was obtained by the solid state method. The manufacturing process of composite materials using the blending method. To reveal the basic properties of the material, morphological analysis, XRD testing, infrared spectroscopy, and density tests were carried out. The results of the study showed the largest reflection loss value was -28,034 dB at a frequency of 10.097 GHz by adding nanocellulose. The correlation of the addition of barium hexaferrite to density has a value of 0.9999. This composite material is designed for the development of materials that are reliable in terms of their sound absorption and radar absorption characteristics.