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.
