The invention provides prefabricated plate type seedbed soil and a preparation method for raising paddy rice seedlings. The preparation method comprises the following steps of: smashing rice hull, blighted grains and straw, mixing according to a certain proportion, adding an EM (Effective Microorganism) microbial agent and water for stockpiling and storing, fully composting, and fermenting to obtain a fermentation mixture; uniformly mixing and stirring the fermentation mixture, perlite, grass carbon, humic acid, a hydrophilizing agent and a multifunctional paddy rice seedling raising conditioner according to the certain proportion, spraying clear water till raw materials are not loosened when extruded into sheets, and stirring uniformly; and extruding into sheets, splicing and drying to obtain the prefabricated plate type seedbed soil. According to the invention, the aims of saving the soil resource, efficiently utilizing resources and maintaining and repairing the weak ecological environment can be fulfilled, high yield, stable yield and sustainable development of paddy rice in cold paddy rice regions, saline and alkaline paddy rice regions and the like are facilitated, and the social benefit, economic benefit and ecological benefit are enhanced.