Abstract: DYZ—1 is a Chinese-made adapted for the microclimate research work in field and greenhouse, forest and mountainous area with high precision. Its principle, design, feature as well as its application effects in the field are described in this paper. The standard deviations of temperature and relafive humidity of the air are 0.1℃ and 1%RH in the range of-25～50℃ and 20～100%RH. This instrument has stood the test of high temperature (36.9℃) and maximum humidity (99%) in the field and shown normal operation and dependable feature. In comparison with Assmannpsychrometer in the field in three di ffrent climate zones of Beijing (temperate zone) , Nanjing (subtropical zone) and Hainan Island (tropical zone), its stan dard deviations of temperature and humidity were 0.23℃ and 1.7%RH in the range of 5～36.9℃ and 19～99%RH, including various errors (radiation, observation, etc.)