The general direction of research work on soil science should be "to study the material composition, properties, cycling and energy transformation of materials in pedosphere and their effects on human living environment, especially on the sustainable development of agriculture",which is a new proposed tendency of studies on soil science under influences of current situation of natural science development and resource environment. Soil science must make an important contribution to that mankind enjoys enough foods and a clean environment. Soil fertility is a primary material base for the establishment of sustained agriculture, and continuously promoting soil fertility to get stable high crop yields via regulating the deterioration and rebuilding processes of soil fertility is the fundamental measure to establish sustained agriculture. Much attention should be paid to the regulation of N, P and K fertilizer ratio and balance fertilization, to the promotion of nutrients recycling in farmlands and to the prevention of soil fertility deterioration. Most important researches of modern soil science in promoting the sustainable development of agriculture in China should involve systematic and long-term experimental studies in many aspects such as sustained agriculture and material cycling in pedosphere, soil fertility and sustainable development of agriculture, and soil water balance and regulation.