The invention discloses a chili special-purpose fertilizer and a preparation method thereof. The special-purpose fertilizer comprises the following raw materials in part by weight: 45 to 55 parts of ammonium nitrate, 10 to 15 parts of monoammonium phosphate, 27 to 32 parts of potassium chloride, 2 to 4 parts of borax and 4 to 8 parts of granulation auxiliary agent. The chili special-purpose fertilizer has reasonable raw material collocation, avoids the phenomenon that peasants blindly fertilize, and overcomes the defects of restricting chili yield because of no boron or nitrate nitrogen in other crop special-purpose fertilizers, and deficiency of influencing yield because of low P2O5 content and no nitrate nitrogen.