The invention discloses blend oil and a preparation method thereof. The blend oil is prepared by blending taking walnut oil as base oil, the blending is scientific, the nutrients are complete, and the nutritional values are high; the ingredients in the blend oil are as follows in percentage by weight: 3.12%-4.18% of saturated fatty acid, 53.6%-60.8% of monounsaturated fatty acid, 15.4%-25.6% of omega-6 linoleic acid, and 9.0%16.0% of alpha-linolenic acid; the ingredients of the blend oil includes walnut oil, linseed oil, grape seed oil, perilla oil, almond oil, sea buckthorn oil, evening primrose oil, rice bran oil, soybean oil, corn oil, peanut oil, rapeseed oil, sesame oil, sunflower seed oil, cotton seed oil, olive oil, cannabis oil, linseed oil, tea oil and additives. The blend oil is reasonable in price, complete in nutrients, long in shelf life, and has special flavor, and the preparation method is simple, and suitable for promotion.