The invention discloses a traceability system based on a block chain, and relates to the technical field of blockchain and information traceability. The system comprises an alliance chain management module, a block chain browser module, a traceability code generation module, an information storage module, an information reading module, a caching module, a commodity information reading module and an SDK module, and the alliance chain management module can manage and maintain block chain nodes and newly add consensus nodes for key link manufacturers on a supply chain in the block chain. According to the traceability system based on a block chain, the information security Tamper-resistant properties of the block chain are utilized;, the information can be protected from being stolen and tampered; the product information can be kept transparent and public in front of consumers; the credibility of the traditional traceability system is improved, the anti-counterfeiting traceability system can adapt to the existing external traceability means on the market, the anti-counterfeiting traceability work of the original product is supplemented and updated, and multiple anti-counterfeiting processes adopted by manufacturers are simplified, so that the labor and financial cost of the work is reduced.