The temperature and humidity characteristics of humidity sensor on China-made GPS and RS92 radiosounding system are studied through a modified test method under controlled temperature and humidity environment in a laboratory.The results show that hysteretic detection occurred under low temperature,especially during the process of humidity increase,which brings obvious error to the dynamic measurement of aerological humidity.The change of airflow also influences the humidity measurement.The obtained results are useful for the modification of humidity measurement algorithm of radiosounding sensor,and the improvement of the measurement performance of aerological humidity sensor.