This is especially true in industries that are heavily dependent on transparent and secure data management practices. Actual audit systems are limited by manual errors, inefficiencies, and the ability for tampering, although they work to some extent. This paper investigates the effectiveness of applying blockchain expansion technology to such a longstanding problem through an implementation of a decentralized, immutable, and highly transparent auditing system. This study analyzes how blockchain can ensure data audit mechanisms with the help of cryptographic hashing, distributed ledgers, and smart contracts. With these features, data accuracy is guaranteed, compliance processes are streamlined, and cybersecurity defenses are strengthened. The comparative evaluation of current audit methods and blockchain capabilities illustrates the potential benefits of lower operational costs, enhanced efficiency, and increased confidence among stakeholders. In this paper, to solve the existing block chain technology data integrity audit scheme, theblockrapidgrowthleadstotheblockchainnetworkmaintenancecostandtheusercreatesthenewblockhighcostproblem, an integrity system is proposed based on block chain expansion technology. 1. Customers and cloud service provider (CSP) deploys smart contract on major chain and on sub-chain. The workload of high-frequency and intensive computing is handed over to the sub-chain to complete, and the multiplication consequences of the sub-chain are periodically or as needed, submitted to the main chain to ensure its finality. The phrase “non-interactive audit” was created to address a customer experience issue brought on by the communication from the CSP throughout the audit process. To ensure data security, an incentive pool system is used. Aspects such as data consistency, batch auditing, and storage demonstrate the scheme’s validity. Our tests on the Ethereum blockchain platform demonstrate that this plan successfully reduces the amount of computing and storage overhead.