Non-pressure Subsurface Drip Irrigation at Crop Root Zone (shortened as Non-pressure Irrigation), is a method of local water control irrigat ion, having pipes with fine apertures buried at the crop root zones.Water oozing out through the apertures under the suction of soil irrigates the crop and satisfies its need during growth.Optimal parameters of the system are-4 to 8 cm in pressure, 10 to 30 cm in depth of buried pipe, and 3 to 8 mm in diameter of the aperture.Comparison between non-pressure irrigat ion and furrow irrigation was carried out to study their effects on movement and variation of soil water, evapotranspiration, relationship between crop yield and water productivity and mechanism of effect of irrigat ion pattern on quality of tomato and cucumber in greenhouse in 2004 and 2005.The results show that non-pressure irrigation improved living conditions of the crops, and left enough oxygen in the root zone so that quality of the crops was raised due to improved distribution of photosynthetic assimilates to different organs.Compared with furrow irrigation, non-pressure irrigat ion did not decrease crop yield, but improved water availability and productivity, and in turn significantly raised contents of vitamin C, soluble sugar, total sugar and inorganic phosphorus, demonstrating its funct ion of adjusting quality with water.