Abstract: Solar energy fixed in green plants, especially in crops, is the source and basis of agro eco-economic system. Ashare of the primary organic products is sold as commodity, a share is consumed by farmers themselves and the others become the carrier of energy and material currents transforming into secondary production. The transformation rate and economic benefit of the crop's by-products are different due to their various utilization ways. Forages, fertilizers and fuels are all necessary in primary production, secondary production and human life. The transformation ways and rates of the "Three Materials" should play a major role in adjusting the structure and function of agro-eco-economic system. In this paper, the major effects of "Three Materials" (3F) transformation are analysed. The technical line of increasing the transformation effect at a greater rate and improving the construction of eco-agriculture is put forward.Its technical key is to ex plore straw resources and saprophagous food Chains.

Key words: Forage, Fertilizer, Fuel, Energy transformation, Eco-agriculture, Saprophagous food chain