Abstract:Based on the observed data of plastic sunlight greenhouse microclimate and neighbouring weather stations during the two winter periods following as 20 06—2007 and 2008—2009, using the method of related statistical analysis, the characters of plastic sunlight greenhouse microclimate a nd the relationship between the microclimate and outside weather conditions in S hijiazhuang area during the winter are studied. The result indicated that the microclimatic factors have obvious diurnal variations under these weather condions such as sun ny day, slight cloud cloudy day. Persistent sunless days can result in lower t emperature and higher air humidity inside greenhouse, which could be harmful to the normal growth of cucumber. The main factors affecting the microclimate were as follows, sunshine hours, average temperature, lowest temperature, highest tem perature, air humidity, cloudage outside and the yesterday’s highest temperatur e inside. The correlation model of weather factors inside and outside the plasti c sunlight greenhouse has been set up, which has high accuracy verified by histo rical data and application. The model’s accuracies of lowest temperature, highe st temperature, air relative humidity, and largest solar radiation under differe nt weather conditions are within 1.1 ℃, 2.5 ℃, 6% and 58.3 W?m-2. Most of the average relative errors are below 10 percent.