Throug hout the controllable analysis of rain resource in semi-arid region,a new waterosmosis plastic membrane was exploited based on validating small rainfall(≤10mm).It can improve rainfall penet ration into soil vertically , modify maximum soil temperature,and ventilate soil,it can also increase soil temperature and block evaporation as conventional membrane does .The patent No.is 97115761.8.In order to raise cropyield in dryland region,small rainfall must be deeply developed.The annual frequency of small rainfall was 70% in semi-arid land in Shanxi province,and the water of it equals to 100mm or more , which has great potentiality of 4tons perhactare land for maize.The tests showed that :the maize covered with water-osmosis plastic membrane had increased by 38.3% in yield,1%～4.5% in soil water than conventional membrane,and 103% in yield than that of no-covered.This new technique can enhance agriculture sustainable development in the 21st century.