To address the issues of data redundancy and data integrity protection in current cloud storage systems， a blockchain-based cloud storage data deduplication and integrity audit scheme was proposed. This approach combined deduplication technology with a blockchain distributed auditing mechanism， ensuring data confidentiality and integrity while achieving deduplicated storage. Firstly， the Message-Locked Encryption （MLE） method was utilized to generate identical encrypted ciphertexts for the same data from different users. For duplicate data uploaders， ownership verification was conducted using a Verkle Tree （VT）-based Proof of Ownership （PoW） mechanism， thus enabling secure ciphertext deduplication. Secondly， based on the immutable characteristic of blockchain， an efficient data integrity auditing mechanism was designed， allowing transparent auditing and verification without compromising user data privacy. This mechanism can defend against various threats， including external attackers， malicious behaviors from Cloud Service Providers （CSPs）， and key management risks. Finally， through functional analysis and security analyses such as key security and resistance to collusion attacks， it is demonstrated that the proposed scheme has high security and practicality. Performance analysis results show that the integrity verification time is proportional to the number of challenge blocks， and when the number of challenge blocks is 1 000， the integrity verification time is approximately 85 ms. Experimental analysis results show that the scheme can provide with reliable deduplication and data integrity auditing services for the cloud storage systems.