Abstract: Under condition of direct sunlight, air temperature measured by conventional sensor is too large．Air temperature obtained by temperature and humidity sensor based on dry and wet bulb principle is closer to real air temperature value by using thermal insulation materials to avoid direct sunlight and forced ventilation．In order to explore air temperature measurement effect of temperature and humidity sensor based on dry and wet bulb principle under condition of direct sunlight, and to quantify measurement deviation of conventional greenhouse air temperature sensor, a comparative study was made on air temperature measurement results of three kinds of greenhouse air temperature sensor of temperature and humidity sensor based on dry and wet bulb principle, thermocouple sensor and SHT35 sensor．Technical principles of three kinds of greenhouse air temperature sensors were summarized, and then experimental data acquisition system and cloud platform were constructed to realize collection and storage of air temperature measurement data．Finally, measured results of three kinds of greenhouse air temperature sensors under direct sunlight condition were compared and analyzed．Results showed that under condition of direct sunlight, air temperature measurement data of thermocouple sensor and SHT35 sensor were obviously higher than those of temperature and humidity sensor based on dry-wet bulb principle．In addition, results also showed that the greater the intensity of outdoor solar radiation, the greater the deviation of thermocouple sensor, SHT35 sensor with temperature and humidity sensor based on dry and wet bulb principle, and on the contrary, deviation was smaller．Data measurement effect of temperature and humidity sensor was explored based on dry and wet bulb principle under condition of direct sunlight, and deviation of measured data of conventional greenhouse air temperature sensor was quantified．It could provide a certain reference basis for selection of greenhouse air temperature sensor．