With the development of the Industrial Internet of Things, the Machine-as-a-Service (MaaS) model is gradually replacing traditional industrial production models and becoming a new approach for manufacturing development in the digital era. Under this model, the Original Equipment Manufacturers (OEM) replace the buyout by leasing. OEM ensures machine availability and shares monitoring data with Machine Users (Mus) by signing Service Level Agreements (SLAs). However, existing SLA Management has defects such as single point of failure, unreliable data, cumbersome appeals, and Mu is concerned about privacy leakage, which hinders fault analysis. To address this issue, this article proposes an SLA management scheme that combines ECDSA digital signature algorithm, which can digitally sign and verify uploaded data to ensure the reliability of monitoring data. Under this scheme, MU and OEM can negotiate to determine SLA measurement indicators and related parameters, and use smart contracts to complete data violation monitoring and automated evaluation during the service process. Finally, case studies and prototype evaluations were conducted through experiments to verify the feasibility and effectiveness of the proposed solution.