Abstract: In order to improve structure of soil in farmland in Beijing area，improve soil water holding capacity，improve agricultural production capacity and increase crop yields，study on the effect of deep tillage farmland was developed in Yanqing county of Beijing city from 2009.Effects on soil bulk density，moisture content，water infiltration rate，crop growth characteristics and yield that using 2 modes of no tillage and deep tillage were contrasted.Test results showed that soil bulk density was reduced from 1.57 g/cm3 to 1.51 g/cm3，reduction of 0.06 g/cm3，reducing about 4%.Average water content increased 5.9%.Good water holding capacity was reflected.Subsoiling operation stable infiltration rate increased 62.5%.Crop yield reached 7.1% by using subsoiling operation than traditional rotary tillage.