A series of studies on knowledge acquisition technology for agriculture domain have been accomplished by the authors and their team for a long term. The artificial and automatic/semi-automatic knowledge acquisition methods using intelligent leading, machine learning, data mining and intelligent computing etc. are described. These methods can acquire domain knowledge more effectively, discovery the potential patterns, and refine the knowledge. And the tools for knowledge acquisition are developed. The methods and the tools show that the knowledge acquisition technology plays an important role in information engineering of agriculture.