The straw stalk cover may reduce the soil surface moisture evaporation , and raise the moisture content use efficiency. By taking the processing without straw stalk cov er as comparison, the observational experiments of the straw stalk cover in whe at and corn growing period were conducted from October 2005 to October 2007. T he experimental result indicates that, th e straw mulching led to changes of meteorological elements near the ground, the air temperature increased, while the vapor pressure near the ground dec re ased, the radiation to the ground was blocked by the straw mulching,the soil tem pe rature decreased, and the moisture content was increased, thus the water use eff icienc y was raised. Meanwhile the straw mulching increased the mature spike number of w heat, and increased the thousandgrain weights of wheat and maize. During the s traw mulching tests, the yield of wheat increased 8.7 percent, and the yield of maize increased 8.9 percent.