To promote environmental education of elementary and secondary school in Seoul for a sustainable development, researchers investigated and analysed the current situation of formal and non-formal environmental education in Seoul as well as their major problems. Based on these current situation and problems, the way to improve the environmental education of elementary and secondary school in Seoul was described. The final section deals with specific recommendations to accomplish the improvement of environmental education of elementary and secondary school in Seoul for a sustainable development as follows: 1) Integration of formal and non-formal environmental education system, 2) Establishment and operation of a regional environmental education center for community, 3) International cooperation, and 4) To provide high quality environmental education programs.