This book focuses on the key technology applied Internet of things and smart grid, which include some novel ICT technologies such as big data, edge computing, 5G, and wide area wireless communication technology. The mutual penetration, deep integration, and wide application of smart grid and IoT effectively integrate communication infrastructure resources and power system infrastructure resources, further realize energy conservation and emission reduction, improve the level of grid informatization, automation, and interaction, and improve grid operation capacity and quality of service. These key technologies are presented and studied in detail, which help readers deeply understand those key technologies to apply IoT and grid. The book benefits researchers, engineers, and graduate students in the fields of IoT and energy systems, etc.