In order to solve the environmental problems in South Asia, in 1980s, the South Asian countries and the India government reached a consensus, decided to set up the South Asian cooperation environment planning department. The establishment of the SACEP is mainly based on consensus following three points: first, realizing that poverty, overpopulation, excessive consumption, waste production etc. factors are causing the deterioration of the environment, being the threat to economic growth and the survival of mankind; second, coordinating the relationship between environment and development is essential for sustainable development of the pre-conditions; third, in South Asia there are many ecological and development issues are beyond the borders and administrative boundaries. As of the beginning of 2015, there are in total of 8 member states: Afghanistan, Bangladesh, Bhutan, India, Maldives, Nepal, Pakistan, Sri lanka. This article firstly introduces the general situation of the cooperation mechanism of SACEP, including the two aspects of organization structure and cooperation aspects; then introduces the overview of environmental cooperation in the SACEP, including environmental protection cooperation agreements have been signed, the items being executed and international cooperation. As of the beginning of 2015, there were 5 major cooperation agreements signed, 11 items being executed between 2008 and 2015; in the aspect of international cooperation, there were dozens of international cooperation mechanisms established.