Abstract: For improving the water-saving capacity in greenhouse, the characters of closed structure, water and energy saving, and purification of Watergy closed greenhouse in Spain was analyzed. Through establishing two models based on evapotranspiration equilibrium, two water balance systems were evaluated, and the possibility of improving condensation in a closed greenhouse was demonstrated. According to the agronomic results, the ability of water-saving and agro-production was pointed out. Two months experiment indicated that the difference between water input and output was only 244 L, which showed a good water-saving effect. The yield of “Strike” beans were 5 times in 2006 (51 kg/m3) in this case comparing with a similar crop growing in an open greenhouse. Lastly, some suggestions for improving the condensation, the future prospects and problems were discussed.