Abstract:Facing thepresent situation of a very largepopulation，arid climateand theserious sand blow by thewind intheplain farmingdistrictofHebei Province in China，we began to plant the fast growing and high yieldforests ofpoplar intercropping withthe crops in the sandy waste land wherethere was a serious sand，in the sandy beach，the second-class cultivated land and the middle-yield and low-yield land in the district from the early part of the eighties，which played an important part in developing and making full use of the land and light energy and increasing the green area and improving the agricultural ecological environment and so on in the district． Temporal and space distribution of microclimate elements，such as temperature，humidity，wind and evaporation， and its effects were analyzed in the poplar-crop intercropping field with different patterns based on the observation data from 1993 to 1997 by artificial and auto meteorological instrument．The results showed that the efficacy of poplar intercropping with crops to prevent wind was 45％～87％，the average value was 57％．The poplar—crop intercropping could decrease daily maximal air temperature from 0.3℃to 3.4℃，with an average of 1.3℃．The daily mean maximal temperature of earth surface could be reduced 6℃by means of the poplar intercropping with crops， the maximal temperature reduced was 19.5℃．The daily mean absolute humidity was increased 0.9 hPa～2.4 hPa with an average of 1.4 hPa，and the daily mean relative humidity was increased l％～l.3％，averaged in 5％．The water evaporation was decreased from 17％to 36％，averaged in 25％．The poplar intercropping with crop could make the continued time of the relative humidity<30％short 4.5 h on a dry hot wind day．Therefore，the poplar intercropping with crops has the obvious functions of wind-proof，dropping temperature，increasing humidity，and de- creasing evaporation，which have significance for improving the field micro-climate and ecological environment of agriculture， and promoting high-yield and stable-yield of agriculture．