The invention discloses a method for producing a seedling breeding container from fibrous solid wastes. The method sequentially includes the steps of (1), smashing raw materials, namely, drying the fibrous solid waste raw materials in the sun, smashing the raw materials and then mixing the smashed raw materials with reinforcements to obtain mixed materials; (2), subjecting the mixed materials to mechanical activating pretreatment to obtain modified fibers; (3), mixing pulp, namely, conveying the modified fibers into a pulp mixing pond, adding waterproof agents with stirring evenly and adding water to dilute to obtain pulp in a solid-to-liquid ratio of 1:(2-6); (4), performing suction filtering molding, namely, conveying the pulp into a mould cavity for suction filtering and dewatering pressing to obtain a wet blank product, wherein filtered water is delivered back to the pulp mixing pond for recycling; (5), performing hot-pressing shaping, namely, transferring the wet blank product into a hot-pressing mould, performing hot pressing under high pressure at a high temperature, and removing moisture generated during hot pressing to obtain the seedling breeding container. The method for producing the seedling breeding container from the fibrous solid wastes has the advantages of simple technology, zero pollution, low cost, high product molding ratio and the like.