This paper examines the global development of intelligent robots, focusing on remote avatar robots. Some key technologies are researched such as mixed reality and teleoperation by analyzing their status, trends, and challenges. Theoretical background and technical solutions for remote avatar robots are explored, covering hardware and software aspects. A new intelligent robot system for hot-line working with flexible arms, force feedback teleoperation controller and mixed reality technology is established. The robot system in the air can fulfill the working like the wire stripping and removal by human teleoperating with mixed reality scene in the ground, meanwhile a security system of UAV with full perception monitoring and active intervention is cooperated in the air. In the end, the article proposes a prototype design integrating teleoperation, mixed reality, and 5G communication for live working in 10KV high-voltage environments, validated through experiments.