Abstract: The paper stated that the agricultural science consists of three main branches, agricultural biology, agricultural engineering and agricultural economics. In the field of agricultural engineering, Chinese people paid great attention to agricultural water conservancy and farm implements in the ancient time to ensure the rich harvest of cereals, cotton and oil crops to supply the people with sufficient main food and fiber. This is why China has been existed in the world for more than five thousand years.Since 1949, the founding of People's Republic of China, Chinese Government still emphasized on water conservency and agricultural mechanization. In 1979, China started her national economy reformation,, Since then, besides water conservancy and agricultural mechanization, Chinese agricultural engineers started to study the following works: rural electrification, agricultural structure and environmental control, rural energy, land utilization engineering, processing of agricultural materials, agricultural engineering economics, agricultural engineering extersion, agricultural systems engineering and the application of computer and remote sensing techniques to agriculture, In 1984, the total annual field of was 407,120,000 tons which is 3.6 times as the total yield in 1949. The whole world recognized that it was an astonishing achievement.In the future time, the paper expects that all the Chinese agricultural engineers should study all the measures in the field of agriculetual engineering to increase the yield per unit area with low production cost of food and fiber to supply the rapid growth of population and heighten the living standard of people.Finally, the paper emphasizes that all the achievements of agricultural industry is impo ssible to get by the agricultural engineering alone, but agricultural engineers must cooperate with agricultural biologists and agricultural economists to work together coordinately for the same target which is the modernization of Chinese agricultrue.