Under the cloud computing environment, the privacy protection in the plaintext state can be realized, by the partition-confusion-based privacy protection mechanism which effectively combines tenants personalized privacy protection requirements and application performance. However, as the multi-tenant applications continue to run, on the one hand, the insertion, deletion, modification and other business operations of the tenant data can affect the distribution of the underlying data storage, making the relationships between the chunks in a significant risk of leakage due to the uneven data distribution; on the other hand, the attacker can still analyze a part of private information by the operation log of every chunk and the snapshot of the corresponding data in the local time. In response to these challenges, the present paper proposes a dynamic data privacy protection mechanism for partition confusion on the basis of the tripartite security interaction model. This mechanism can cache the data newly inserted and modified by a trusted third party and then group and upload it under the proper conditions; retaining key fragmentation in the deletion operation can ensure the privacy of the deleted and remained data; the falsifying data collection mechanism can achieve lower consumption of resources storage and optimize the application performance. The experimental result proves that the dynamic data privacy protection mechanism proposed in this paper has better feasibility and practicality.