The invention provides a biological organic / inorganic compound fertilizer. The biological organic / inorganic compound fertilizer contains 30-35% of total nutrients; the nutrient ratio of N to P2O5to K2O is (6-15) to (5-18) to (6-25); the living bacteria count in the bioactive organic insecticide-fertilizer is 50 million / g to 100 million / g; besides, the biological organic / inorganic compound fertilizer contains 15%-25% of organic matters, 0.15-0.20% of nicotine, less than or equal to 3.0% of chloride ions and less than or equal to 12% of moisture, has the fineness of 40-60 meshes and the pH of 6.0-7.0. The preparation method of the biological organic / inorganic compound fertilizer comprises the following steps: adding tobacco stems, cake meal, pig manure, artificial humic acid and a microbial fermentation agent to a mixer, adding water while mixing, and composting the materials for fermentation to obtain the fermented and decomposed materials; next, adding the fermented and decomposed materials, urea, ammonium dihydrogen phosphate, potassium chloride, active carbon nanopowder and a functional microbial agent to the mixer, mixing evenly and crushing, screening to obtain powder and packaging to obtain the biological organic / inorganic compound fertilizer which is high in content of nitrogen, phosphorus and potassium inorganic nutrients and organic matters, and has environment-friendly and insect-resistant effects.