The flame sensor uses thermal radiation induction judgment and the Curie temperature of lithium carbonate crystal materials to accurately detect and warn flames with flame temperatures above 250-4000℃ and wavelengths of 380-750nm. The relative dielectric constant is small, and within a wide range of room temperature, there can be obvious temperature difference and high contrast polarity changes for fire warnings. The detector has stable performance. When a fire occurs, it can quickly capture and respond to trigger an alarm within 1 to 2 seconds. It is used for various types of open flame induction fire warnings: fire warnings, security warnings, industrial plants, mining areas, chemical combustible alarms, family homes, charging piles, gas stations, chargers, equipment and machinery, etc.