The invention discloses a special fertilizer for a cotton base fertilizer. The special fertilizer is prepared by silkworm excrement, wintergreen oil residue, decomposed coal, diatomite, biological bacteria, urea, diammonium hydrogen phosphate, potassium sulfate, goose feather bar, carboxymethylcellulose, 35% of sulfuric acid, lime, zinc sulfate, magnesium sulfate, manganese sulfate, nanometer iron-ore tailing powder, sweet wormwood extract, azadirachtin and wintergreen oil according to a certain weight ratio. According to the special fertilizer, amino acid is generated by feathers after acid hydrolysis, trace elements or secondary elements are cheated, and a chelate structure of the trace elements or the secondary elements is reinforced by the carboxymethylcellulose, so that the trace elements or the secondary elements can be effectively utilized and ineffective releases of the trace elements or the secondary elements can be reduced; an inorganic slow release component and a soil improvement component, namely the diatomite and the decomposed coal, are added in a formula of the special fertilizer to improve the soil and to be beneficial to the effective release of fertilizer efficiency and full absorption of the fertilizer by the crops; biological insecticide components, namely the nanometer iron-ore tailing powder, the sweet wormwood extract and the azadirachtin can effectively reduce pest and disease damage of soil, are safe and pollution-free, and do not pollute an environment or the crops; and the special fertilizer has the advantages that the formula is reasonable, the nutrition is more comprehensive and balanced, the use effect is good, the utilization rate of fertilizer efficiency can be remarkably increased, the yield and the quality of cotton are greatly improved, and the economic benefit of the cotton is increased.