This paper puts forward a power quality information condition monitoring platform suitable for smart grid. It introduces the ontology technology into the construction of the platform and sets up domain ontology in the field of power quality condition monitoring. With the aid of the domain ontology, it can realize fast power quality information retrieval. The power quality information condition monitoring retrieval engine established under the guidance of domain ontology can extract eligible data set from the power quality database, and then return the result to the user. The platform introduces the technology of cloud model to complete the diagnosis of power quality information, in order to realize condition diagnosis and real-time monitoring of power quality information based on cloud model. Examples exhibition introduces the operation interface of the platform and implementation interface, and it can be found the platform has a certain engineering practicability.