With the continuous development of the informatization level, the construction of an ubiquitous power Internet of Things (IoT) is put on the agenda. This has important guiding significance for improving the online monitoring level of substation power equipment and promoting the development of the smart grid. This paper studies the power equipment condition monitoring system based on the IoT, and summarizes the architecture and characteristics of the ubiquitous power IoT online monitoring system. Given the requirements of on-line monitoring of substation power equipment status, the system structure of an infrared thermal imaging monitoring subsystem and substation environmental monitoring subsystem is explored, and the optimal design of a power equipment condition monitoring system is realized. The planning, design and construction of a substation power equipment condition monitoring system are covered. These have very broad application prospects.