Gas-insulated equipment (GIE) that utilizes the most potent greenhouse gas sulfur hexafluoride (SF6) as insulation and arcquenching medium has been widely used in the power industry. Seeking eco-friendly insulating gas with advanced performance for next-generation SF6-free GIE is significant for the “net-zero” goal and sustainable development. In this paper, the utilization, emission, and reduction policies of SF6 around the world were summarized first. Then, we systematically reviewed the latest progress in comprehensive performance evaluation of eco-friendly insulating gas in terms of molecular design, dielectric insulation, arcquenching, stability and decomposition, materials compatibility, biosafety, etc. Further, the representative applications of ecofriendly insulating gas in medium-voltage, high-voltage GIE as well as relevant maintenance-related technologies were highlighted. Accordingly, the existing challenges and future perspectives were proposed, presenting a roadmap to hopefully steer the development of eco-friendly insulating gas and GIE.