Large, complex, expensive, and long-lived equipment often operate in harsh environments, which leads to the requirements of lifecycle maintenance, repair, and overhaul (MRO). To support the continuous improvement of productivity and to reduce the cost of MRO, this paper developed a cloud-based framework for lean MRO of the equipment with the aforementioned characteristics. A concept and a model of lean MRO are proposed. Taking advantage of cloud-based design and manufacturing (CBDM) into account, an architectural framework of cloud-based MRO is proposed. A case of a lean MRO for continuous casting equipment demonstrates that the proposed cloud-based framework can achieve the goal of lean MRO of complex equipment.