The invention discloses a clustering monitoring and diagnosing system for mobile offshore oilfield equipment. The clustering monitoring and diagnosing system is composed of an equipment document module, an integrated checking and maintenance part, a fault library module, an integration module, a spare part information module and a spot checking management module. The integrated checking and maintenance part includes a state monitoring module. The state monitoring module collects an equipment state monitoring parameter, carries out fault early warning by using an amplitude analysis, carries outa fault analysis by combining an atlas analysis, writes a diagnosis report, and guides the equipment for maintenance. A start-up or shut-down state change of the equipment is determined; and when theequipment is in a shut-down state, an equipment maintenance plan and an equipment checking plan are formulated and maintenance process information and checking process information are recorded. And needed data are dug and a relevant KPI management report is outputted. According to the invention, state monitoring parameters of equipment including the pump, the internal combustion engine, the reciprocating compressor and the centrifugal compressor can be collected to realize the fault early warning and fault diagnosis; the diagnosis report is written; the maintenance task is optimized; the equipment maintenance is guided; and the KPI management report is generated.