The invention relates to the field of food processing, in particular to a sauce and a preparation method thereof. The sauce is prepared by the following raw materials in certain proportion according to steps: morel umami material, fresh beef, soybean paste, salad oil, beef tallow, sesame oil, raw green onion, minced garlic, spices, light soy sauce, white sugar and salt. The sauce has both the umami of the morel and taste of other raw materials, and is strong in umami, unique in flavor, natural, healthy and nutritional under the condition of monosodium glutamate absence.