Plunting grash in fields was an important measure of the structural adjustment of cropping system from cereal-cash two-unit
structure to cereal-cash-forage three-unit structure,and was also the key to realizing the combinution of farming with animal husbandry and to building the grass-livestock-milk meat integrative cropping patterns.The paper discussed the basic concepts and the economic implications of planting grass in fields;it analysed the risks to take and the existing problem from the angles of the present actual situation and the trend of the productive development;it puts froward the
preventive countermeasures against the risk of planting grass in fields.The results showed if planting grass in fiels should rationally practised accordingly to the demand based on the precise analysis of international market information and the local natural resources.the ceonomic basis and the social environment,it would be feasible to form the variety of agricultural products so as to ment with the market demand,to increase the in come of famiers and herdsmen and to promate the sustainable development of agriculture.