Reliability of manufacturing resources is an important measure for ensuring quality of service (QoS) and for carrying out service evaluation, and trust modelling in a cloud manufacturing environment. However, no extensive study of this measure has been carried out. In this paper, we propose a hierarchical reliability assessment model to assess manufacturing service reliability. First, we evaluate the reliability of manufacturing resources within an enterprise at three different levels, i.e. component, machine and system level. Then, the system level is extended to form collaborative systems among distributed manufacturing resources by considering logistic reliability. Second, the reliability of the cloud system is also assessed. Finally, by identifying the relationship among different levels of reliability, we formulate the reliability of the entire cloud manufacturing system. A real world case study is presented to demonstrate the feasibility and effectiveness of the proposed model. © 2018 The Authors. Published by Elsevier B.V.