In order to adapt to the trend of unattended substation, improve the debugging and maintenance efficiency of substation automation device, and at the same time meet the demand of flexible expansion of operation and maintenance business, the remote operation and maintenance technology of substation automation device based on micro-services architecture is studied. Firstly, the architecture and functions of the system are designed according to the operation and maintenance requirements. Secondly, the edge computing platform is developed, and the operation and maintenance business is realized by application (App) programs based on container technology. The plug and play process of device and Apps are designed, and active online interaction protocols are proposed. Finally, a operation and maintenance gateway based on micro-services technology is developed. The gateway has the characteristics of universal hardware, software decoupling and flexible functions. Apps such as virtual human-machine interaction, software version control, operation and maintenance debugging are developed. The system has been applied in a 220 kV substation in Nanjing, and the operation and maintenance efficiency is improved.