The purpose of this study is to investigate the environmental value of green space in Seoul. Longitudinal relationships between land use patterns and $SO_2/NO_2$ have been analysed. Then the environmental and economic value of green space were examined. In this study, the following results have been found : Firstly, it was found that the amount of $SO_2$ showed the negative relations with green space but had the positive relationships with the built-up area. Which in turn can be interpreted as securing the green space could improve the $SO_2$ purification capacity. Secondly, Seoul Metropolitan green belt zones absorbed 69,728 tones of $CO_2$, 654 tones of $SO_2$ and produced 51,205 tones of O2 at the year of 1997 standpoint. This results implicate that the Seoul Metropolitan green belt zones resolve 0.2% of $CO_2$ and 2.9% of $SO_2$ production in total. Finally, the occurrence of an additional costs of 6,800 Korean Won per household was expected due to the air conditioning cost increases as the green belt areas decrease. Therefore, it is recommended to establish the alternative plans for the protection and creation of the green space in the urban areas, since those urban green space have the significant meaning as their provision of habitats for the wildlife as well as their contribution to the reduction of energy consumption.