Abstract: The philosophy, methodology and limit of traditional Chinese Agronomy and western Agronomy are discussed in this paper. Traditional Chinese Agronomy is based on Chinese classical philosophy and interprets agricultural phenomena from original macrocosm. Western Agronomy is based on atomism and observes things by the way of experiment. Modern systems science develops in 20th century which explores macrocosm, evolvement and complexity. In this paper it is pointed out that philosophy and methodology of modern systems science should be adopted and developed by modern agronomy.