The invention discloses oil marinate in secret formula, which includes following raw materials: refined oil, cooked rapeseed oil, soup-stock, dark soybean sauce, salt, chicken essence, Chinese pricklyash, dry chili, chili powder, monosodium glutamate, Chinese onion, raw ginger, rock sugar, star anise, fennel, cloves, alpinia katsumadai, lysimachia sikokiana, fructus amomi, rhizoma kaempferiae, amomum tsao-ko and cinnamon bark. A preparation method includes: 1) washing and blanching the marinating raw materials, adding the raw materials to marinade, heating the marinade to boiling, stewing themarinade on soft fire, and when the raw materials are 80% cooked, moving out and draining the raw materials, and air-cooling the raw materials; 2) placing marinating oil in a marinating pot, heatingand boiling the marinating oil and adding the marinating raw materials in the step 1) to the marinating pot for marinating the raw materials; 3) moving out the marinating raw materials, and when the marinating oil is cooled, soaking the marinating raw materials in the marinating oil. The product has unique flavor, high nutritional value and strong fragrance, is long in shelf life and is easy to transport and store.