The aim of this study is to increase children’s social-emotional development using project approach on early childhood environmental education. The researcher uses applied classroom action research method to explore the project approach on environmental education as multidimensional approach. The project approach is in-depth investigation to a topic which has three phases; 1) planning and getting started, 2) developing project, and 3) reflection and conclusion. This study involved collaborators and 15 children organized in two cycles. The findings are as follows. The children’s social-emotional development has been increasing by the end of cycle-2, their social-emotional development level especially in giving respect to others and borrowing or lending toys has been increasing significantly as well as their capability on taking part in large program or agenda. Another finding in this study is the instructional activities during the project approach on early childhood environmental education has been giving children opportunities to interact actively with people around since these are the basic of social-emotional development.