Abstract: The water condition of Aneurolepidium chinense community was studied in A .chinense grassland in Northeast China by method of the artificial climatic chamber. The results showed that under the condition of typical climate(clear day),all of the diurnal curves of the transpiration rate (Tr) and evapotranspiration rate(ET) of A. chinense community in various peroids of the growing season were of the double-peak type. There existed positive correlations between Tr (ET) and solar radiation and air temperature, and negative correlations between Tr (ET) and air relative humidity. There existed a negative correlation between the ineffective water lost ratio (IR) and Tr. Tr of plants in the community was the highest in florescence, which was 1.156g·cm-2·d-1;Tr of the community reached its highest value,which was 4861.07g·m-2·d-1,in late July. The highest value of ET happened in late June,which was 6454.36g·m-2·d-1. Monthly Tr and ET had their highest values,83.9mm and 125.9mm,in late August and late June respectively. The water consumption of the community and the precipitation equaled roughly within the whole growing season,but the seasonal variation of the two were not alike,so there was a serious water deficit in June,which is the early peroid of the growing season. This makes the community unable to use the abundant precipitation fully and effectively and productivity was therefore not high.