A provided medicine feed additive for promoting growth of weaned piglets and improving immune function comprises the bulk drugs: radix campanumoea javanicae, semen euryales, garlic, fructus crataegi, acanthopanacis senticosi radix et rhizomaseu caulis, corni fructus, root of przewalsk euonymus, siegesbeckiae Herba, root or herb of rose mallow, achillea alpina, concretio silicea bambusae, aster ageratoides, ootheca mantidis, fructus broussonetiae, dioscoreae spongiosae rhizoma, dendrobii caulis, fructus citri sarcodactylis, radix panacis quinquefolii, fructus litseae, radix curcumae, hippophae fructus, scutellariae radix, coriolus, herb of oblongleaf betony, saururi herba and balanophora involucrate. The medicinal feed additive is capable of promoting metabolism of piglets, promoting growth, improving production performance, improving immunity of piglet bodies and preventing diseases, and is capable of preventing medicine residue in piglet bodies and free of toxic and side effects compared with antibiotics, hormones, chemical synthetic drugs.