The utility model relates to agricultural machinery, and particularly relates to a water culture device for plant seedlings. The water culture device for plant seedlings is mainly characterized by comprising a plurality of layers of supports arranged on a water culture frame, a plurality of culture devices are arranged on the supports, an air pump is fixedly connected on the water culture frame or the supports and an air pipe of the air pump is connected with an air stone of every layer of culture device. The water culture device provided by the utility model has the advantages of being simple in structure and convenient to operate, is capable of effectively fixing the water culture plants and can simply and conveniently take out and return the plants under the condition of not damaging the plants; meanwhile, nutrient solution change, drainage and other operations can be conveniently realized, the differences caused by culturing different plants, different varieties, or individuals can be reduced by separating root systems, the dosage of the water culture nutrient solution can be precisely controlled to avoid the influence on the water culture, so as to reach a desired purpose; in addition, the plant cultivation is not limited by the time, can be tested in a small scope and can be cultured on a large scale. Compared with a traditional culture method, the method is convenient to install and low in cost, thereby being specially applicable to perform the scientific experiments of all measurements in the cultivating process.