The invention discloses a method for cultivating mechanized transplanted seedlings of rice by use of an organic medium 
production line in a gutter-connected plastic 
greenhouse. The method comprises the following steps of 1), arrangement of cultivating 
seedling materials, namely a medium, a 
seedling disk, a dome-shaped steel-structure 
plastic film gutter-connected glasshouse facility, and a finishing 
seedbed; 2), 
seed treatment, namely choosing seeds, soaking the seeds and accelerating 
germination; 3), medium treatment and 
disk loading, namely firstly loading a bottom-layer medium, then seeding, finally covering the seeds with the medium and watering; 4) seeding and 
bud promotion, namely seeding dry rice and 
bud rice in each disk, stacking the disks and promoting 
bud, moisturizing, warming, arranging the disks, and performing atomizing spray, wherein the disk stacking height is 20 
layers; and 5) 
seedling stage management, namely attentively managing the temperature and 
moisture and controlling diseases. The method has the advantages of good technical effect, obvious social benefit and prominent economical and ecological benefits and the like, and the method has preferable popularization prospect.