Introducing the current research status in the field of dew?point temperature sensors, and expounding the principles and structures of optical, resonant, electrical, thermal, weight and chemical dew?point temperature sensors. It is pointed out that the optical dew point temperature sensor has high measurement accuracy, and the cold mirror dew point sensor can be used as the humidity measurement standard. The resonant dew point temperature sensor has the characteristics of small size, low cost, short response time, high sensitivity and good reliability. The electrical dew point temperature sensor has high sensitivity and low power consumption, which is convenient for miniaturization and integration. Gravimetric method is the most accurate absolute humidity measurement method and the basis for establishing humidity benchmark. Chemical methods are often used to measure organic gas mixtures in low humidity. The application of dew point temperature sensor in environmental monitoring, industrial manufacturing, medical diagnosis and other fields is discussed. It is pointed out that dew point temperature sensors will develop towards high precision, high stability and high response in the future, and their application range will be further expanded to meet the measurement needs in extreme environments.