<p>6G cloud data security auditing is essential to ensure the network security operation. However, three key challenges must be addressed in 6G cloud data security auditing. First, in 6G network, current auditing scheme cannot simultaneously meet the requirements of security auditing and traceability for 6G network cloud data. Secondly, the cloud data security auditing based on the single-user policy cannot realize the batch security auditing of the cloud data of 6G massive users. Finally, multi-node traceability in cloud data security auditing is an urgent problem that needs to be solved. To address these three challenges, we first built a cloud data security auditing architecture based on blockchain to meet the 6G cloud data security auditing and traceability requirements. We then propose a cloud data security auditing scheme based on an improved CPoR algorithm and a traceability scheme based on the multi-key linear homomorphic signature algorithm. They achieve batch security auditing of cloud data under 6G massive users and multi-node traceability during auditing. Moreover, we validate the effectiveness and safety of the proposed schemes through correctness and safety analysis. Finally, we conduct a comparison experiment for our scheme. In the proposed security audit and traceability scheme, when the number of users reaches 2000, the time consumption for signature aggregation is decreased by 91% and 36% respectively, and the time consumption for verification is decreased by 90% and 18% respectively. When the number of data blocks is 2000, the time consumption for signature aggregation is reduced by 67% and 10% respectively, and the time consumption for verification is reduced by 91% and 70% respectively. Experimental results show that our scheme has better comprehensive performance.</p>