The　efficiency　of　the　existing　PBFT　consensus　algorithm　in　the　alliance　chain　will　become　very　low　after　the　network　nodes　reach　a　certain　scale,　and　the　number　of　nodes　in　the　network　is　fixed　and　lack　of　dynamics.　Because　food　merchants　need　to　be　added　dynamically　in　the　food　traceability　system,　the　classical　PBFT　consensus　algorithm　is　not　applicable　in　the　food　safety　traceability　system.　To　solve　this　problem,　this　paper　improves　the　PBFT　consensus　algorithm　based　on　subject　credit　to　adapt　to　the　traceability　scenario　of　food　supply　chain.　In　the　aspect　of　node　expansion,　a　node　expansion　mechanism　is　proposed　to　increase　the　dynamics　and　flexibility　of　the　network　on　the　premise　of　ensuring　the　network　scale;　In　view　of　the　random　selection　of　the　master　node　in　the　original　PBFT　consensus　algorithm,　which　may　lead　to　the　insecurity　of　the　master　node,　a　master　node　selection　mechanism　based　on　credit　is　designed　to　enhance　the　security　of　the　master　node　and　improve　the　success　rate　of　the　consensus　process.　©　2022　ACM.