The invention discloses a combined loan service platform based on a block chain and a loan management method, and the combined loan service platform mainly provides combined credit for borrowers for amain loan financial institution and a small loan participation company, loans the borrowers according to an agreed capital proportion condition, and undertakes risks according to an agreed risk undertaking mode. And the platform registers and uplinks asset information and basic information of participants by using a block chain technology, so that tamper resistance of data is realized, and data reliability is ensured. And the platform combines big data risk control and a knowledge graph, carries out portrait and association network construction on customer data, and provides risk management and early warning after lending of a borrower. And the joint loan business platform is also connected with other transaction platforms to realize participant asset transfer requirements and self-financial requirements, so that the liquidity of funds of small loan companies is improved. The combined loan business platform is also connected with an industry supervision system, thereby simplifying theflow of small loan enterprise data reporting, and facilitating the real-time supervision of a supervision department for the small loan industry.