Human health is being threatened for excess nitrate intake through dietary pathway (vegetables and drinking water) worldly,and vegetable is the primary source (about 80%) for its large quantitative ingestion and their biological characteristics of nitrate accumulation,especially for leafy vegetables (e.g.lettuce,Chinese cabbage,spinach etc.).Soilless cultivation is the international tendency of vegetable production,but soilless cultivation is regarded as a production pattern that is easy to lead to high-level nitrate accumulation in leafy vegetables for high concentration nitrate supply.