The invention relates to a preparation method of clay-contained duck feed. The preparation method includes the following steps: (1), heating natural clay in water for dissolving, obtaining clay leachate through filtering, dewatering the clay leachate for concentration, sterilizing by using ultraviolet rays to obtain concentrated clay paste, and obtaining clean clay powder for standby use after dehumidifying and drying; (2), after washing, drying and sterilizing corn, sweet potato powder, bean pulp, dried viviparus, rice bran and ground beeltle, smashing into particles of 1-3mm in diameter, and weighing and mixing the particles according to weight to form a particle mixture for standby use; (3), using clean water to wash folium isatidis, agrimonia pilosa, reed root and bamboo shavings, boiling in water for 30 minutes after washing, adding edible salt, calcium hydrophosphate, seaweed meal, fish oil, zymophyte and citric acid, continuing to boil for 10-15 minutes, filtering out impurities, and taking filtrate for standby use. By the clay-contained duck feed, ducklings can fully absorb trace elements in a natural and sanitary state, so that yield and quality of the ducklings are improved.