It is of great importance to ensure the safety

reliability as well as economic efficiency of power grid for the accurate condition assessment and appropriate operation maintenance strategy of the key power equipment. As the rapid development of the smart grid technology

the information technology

the intelligent operation

and maintenance technology

the power equipment data possess the characteristics of big data

such as volume

variety and velocity. It becomes a huge and urgent challenge to make the best of the multi-source heterogeneous data

clarify the association relations deeply between the different types of the data and the equipment conditions

and achieve the differential and accurate evaluation results under different operation conditions. Consequently

we introduced the sources and features of the equipment data

the improvement methods of data quality

and the extraction methods of the condition characteristic parameters. Moreover

we analyzed the research status of the condition assessment method and the fault diagnosis method for power equipment

pointed out the advantages of the big data analysis method though several application examples

and summarized the features of big data analysis method. Finally

we briefly analyzed the challenges of the condition assessment for power equipment.