Hydroxyethyl cellulose-bamboo charcoal (HxBy) hybrids with different content ratio were applied to develop a biochar hybrid filler for natural rubber (NR) reinforcement. The hybrids were conducted with hydroxyethyl cellulose and bamboo charcoal by a hydrogel-adsorption method, and the NR composites filled with hybrid fillers were synthesized by interpenetrating polymer network (IPN) method. The curing properties of the NR composites were tested by a rubber processing analyzer (RPA-V1), the morphological structure of the composites were characterized by SEM. and the dispersion characterization of the composites were characterized by dispersion tester. Tensile strength, hardness value, rebound value, friction coefficient, abrasion resistance and swelling ratio were investigated to verify the property improvement of the NR composites. From the results of all the tests, it could be found the hybrid H8B2 (Hydroxyethyl cellulose: bamboo charcoal = 8:2) showed the best reinforcement, the probable reason is the hybrid H8B2 could provide the best interpenetrating network structure.