Major causes of ecological environment situation and rural environment issues in the construction of new socialist countryside in China are analyzed. Two necessities of introducing circular economy development mode of eco-agriculture and forestry into the construction of new socialist countryside are expatiated. One is the needs of the rural eco-environmental situation, and the other is to realize the fundamental change of agricultural growth mode. Specific characteristics, existing foundation and current resistance of the circular economy of eco-agriculture and forestry are studied. Major principles in introducing circular economy mode of eco-agriculture and forestry into the construction of new socialist countryside are presented. Support system for constructing the circular economy mode of eco-agriculture and forestry is discussed, including the improved government function and regulatory mechanism, marketing organization, farmers professional cooperative organization, leading enterprise, circular economic market system of eco-agriculture and forestry, and human resources. Taking Huaping County, Lijiang City, Yunnan Province, China as an example, “919” circular economic model in this county and its development result are analyzed.