A seedling-raising and root-shaping agent for inserting into the plate of a rice seeding machine and application method thereof are disclosed. The root-shaping agent comprises an auxin-like plant growth regulator (with a content of 1-10 ppm) and sodium dichloroisocyanurate (with a content of 50-200 ppm). The root-shaping agent can promote the growth of the machine planted seedling, generate the tiller in advance and increase effective spike to dramatically improve the output of the rice and has simple and convenient use including two application methods of soaking seeds and spraying.
