Cloud computing can provide on-demand resource services for customers, but also faces server downtime and security issues. The cloud Service Level Agreement (SLA), as a compensation agreement between customers and service providers, has some problems such as non active execution, disputes and infringement. Existing SLA monitoring solutions either lack multi-party trust, have weak audit ability, or have privacy issue. To address the above problems, a blockchain-based cloud SLA violation monitoring and auditing model is proposed. This model provides multi-party trust through blockchain, ensures data authenticity by a dual monitoring method and keeps monitoring result securely stored on the blockchain by appling trapdoor order revealing encryption algorithm (TORE). Besides, a smart contract is designed to automatically perform auditing tasks to ensure credible violation judgment and privacy preserving. At last, some punishment strategies for violations are introduced, which can distribute compensation or change user’s reputation with smart contracts. With experiments, we exam the cost of the blockchain-based system and demonstrate the feasibility of our proposed model.