Exploring new ways to utilize carbon black of by?products of acetylene production from natural gas is of great significance for realizing the efficient utilization of resources，promoting the economic growth of chemical enterprises and reducing environmental pollution.In view of the poor surface activity of by?product of acetylene production from natural gas that limits its application in the field of reinforcement，the method of in?situ synthesis of by?product carbon black with silica was proposed to prepare composite materials，and the obtained products were used to reinforce styrene butadiene rubber.The samples were characterized by scanning electron microscopy（SEM），thermogravimetric analysis（TGA），infrared spectroscopy（FT-IR），oil absorption value，contact angle，particle size analysis（DLS） and electronic universal material testing machine.The results showed that the white carbon black was coated on the surface of by?product carbon black successfully by in?situ recombination method，and the amorphous carbon black was transformed into a regular spherical structure，the particle size of D₅₀ was increased from 9.54 μm to 30.04 μm，the oil absorption value was increased from 1.2 mL/g to 3.04 mL/g，the contact angle was decreased from 85.62° to 38.29°，which meant the hydrophilicity was obviously enhanced.The reinforcement effect of by-product carbon black/white carbon black composite on styrene butadiene rubber was better than that of single by?product carbon black.And the Shore A hardness was increased by 10%，tensile strength，elongation at break and tensile modulus （300%，500%） of the modified carbon black reinforced rubber were 60%，14%，10% and 13% higher，respectively.The development of this composite material expanded the scope of carbon black resource utilization，and effectively boosted the green and sustainable development of natural gas chemical industry.