Abstract: In the power system, temperature changes will damage part of the equipment, and eventually lead to the increase of contact resistance, resulting in a great danger.Passive wireless temperature sensing is an important way to ensure the safe operation of the power system.Near-zero-index (NZI) is characterized by deformability, local tunability, field enhancement, etc., with great potential applications in sensing and other fields.By placing a quartz tube filled with distilled water in the substrate integrated waveguide to construct near-zero medium, a passive wireless temperature sensor based on nearzero medium is proposed.Since the dielectric properties of distilled water changes with the temperature, the change of the temperature can be effectively monitored by observing its transmission characteristics.In this way, abnormal information of the equipment can be timely collected and processed to ensure the normal operation of the equipment.