The purpose of this study uses agricultural knowledge system theory to explore how the extension system in South Korea was developed and have worked well. By agricultural knowledge system we emphasized the dynamic networks of actors, processes of negotiation, and the diverse ways in which knowledge is constructed and performed. It was possible that individuals may participate in and utilize multiple knowledge systems. The knowledge systems reflected the idea that the boundaries between knowledge groups were not closed and that there could be considerable overlap between knowledge systems. The constructions of agricultural knowledge systems thus included social interactions, communication, and the diverse processes individuals employ to create, use, and evaluate multiple types and sources of information. As such, there were six priorities to development agricultural extension system; the linkage between agricultural colleges, Rural Development Administration(RDA), branch of RDA, establishing the research institution of research and extension linkage. exchange research agent with extension agent, developing information technology system, bottom-up approach, the linkage between national project and regional within extension projects, enforcement of informal learning.