The invention discloses a culturing method of plantlets of rear tree erythrophloeum ferdii. The seeds of the erythrophloeum ferdii are sown by adopting a conventional method. The method is characterized in that the mixed matrix of yellow subsoil and biogas residue is arranged on the lower layer of a seedling cultivating matrix, and pure yellow subsoil is arranged on the upper layer of the seedling cultivating matrix, biogas slurry, seaweed oil and a compound fertilizer are mixed to be used for cultivating an additional fertilizer to obtain the good and healthy plantlets of the erythrophloeum ferdii. According to the method, the fertilizer damage as the epidermises of the seedlings which are transplanted just now are tender and sensitive to the fertilizer can be effectively prevented by the cultivating matrix; when the seedlings recover to grow new roots, the biogas fertilizer on the lower layer can be conveyed upwards slowly along with water content, so that the seedlings can absorb the nutrients needed by the growth in time; the biogas slurry, the seaweed oil and the compound fertilizer are taken as the additional fertilizer to be applied in a matching manner, so that the purpose of making good for deficiency is realized, and the fertilizer efficiency is improved; and the resources of raw materials are sufficient, the cost is low, the method is simple, the operation is convenient, the nutrition content is comprehensive, the absorptivity is good, the survival rate is high, the growth of the seedlings is facilitated due to the combination of rapid release and slow release of the fertilizer effect, and the culturing method adapts to the demands of accelerating the development of the rare and endangered erythrophloeum ferdii.