The invention belongs to the field of planting technologies, and particularly discloses an additive for baphicacanthus cusia bremek fertilizers and a method for preparing the additive. The additive is made of fructus tsaoko, murraya paniculata, mesona chinensis, rhizoma ligustici, herba violae and maidenhair tree bark. The additive and the method have the advantages that synergistic effects can be realized by medicines by means of reasonable compatibility design, growth and development of baphicacanthus cusia bremek plants can be promoted, the yield of baphicacanthus cusia bremek can be increased, particularly, the disease resistance of baphicacanthus cusia bremek seedlings can be improved, and the survival rate can be increased; process parameters are regulated and controlled, accordingly, the utilization rates of raw materials can be increased, and additional value of the additive which is a product can be increased; the powdery additive prepared by the aid of the method is favorable for transportation, storage and application.