On-line monitoring system, with functions of status monitoring and early warning, combines modern sensor technology, automatic measurement and control technology, computer application technology, threshold algorithm, model self-correction and specialized analysis software and communication network technology. Especially Distributed Multiple Components Monitoring System is used to collect and transmit the basic and key information, which uses characteristic sensor for the key points of key components. The data will be uploaded to the cloud monitoring platform by wire or wirelessly and the cloud platform will do processing as well as storage and provide visual diagnosis display interface. This system can be used for on-line monitoring systems for the key components of rail vehicles, military key components and the whole system and wind power equipment, industrial metallurgy, electric power, water quality, atmosphere and environment etc.