In order to study the effects of regulated water deficit irrigation on soil moisture and temperature regimes in summer corn field of North China under subsurface drip irrigation, soil moisture and temperature, as well as canopy temperature, plant height, leaf area index, yield of summer corn in the whole growth stage were analyzed on the basis of a field experiment in Beijing. The results showed that the treatments, except for severe water deficit treatment, kept soil moistures in 20~60cm soil layer within a high and stable range; soil moistures for the well-watered control were higher than that for other water deficit treatments in 60~100cm soil layer; in all different soil layers, soil moistures had little differences for low and moderate water deficit treatments. Influenced by the degree of crop cover and water deficit, differences of soil temperatures and canopy temperatures among treatments were remarkable in the jointing stage; in upper soil layers (30~50cm), soil temperatures for the well-watered control were lower than those for other water deficit treatments before the jointing stage, but the differences among treatments were reduced after that; in deeper soil layers (80cm), the higher the deficit degree was, the higher the soil temperature would be. Finally, low water deficit treatment had higher corn yields, and moderate water deficit treatment greatly raised irrigation water use efficiency. 