The invention belongs to the technical field of seasonings, in particular relating to a salad sauce with mustard flavor and a preparation method thereof. The salad sauce with mustard flavor is prepared from the following raw materials in parts by weight: 20-70 parts of salad oil, 35-70 parts of water, 5-20 parts of plain white, 1-8 parts of monosodium glutamate, 1-10 parts of salt, 5-15 parts of sugar, 3-15 parts of powdered milk, 1-10 parts of acetic acid, 0.3-3 parts of xanthan gum, 3-15 parts of mustard powder, 0.5-5 parts of emulsifying agent, and 2-10 parts of modified starch. The salad sauce with mustard flavor is prepared through the following steps: preparing for the raw materials; weighing the raw materials; dissolving the raw materials, and heating up to 90 DEG C-95DEG C; addingthe salad oil and the plain white after cooling to 60-70 DEG C; adding the acetic acid and the water, stirring, homogenizing and emulsifying into the salad sauce; and carrying out quality inspecting,and packaging to obtain the finished product. The salad sauce with mustard flavor has the advantages of low fat, nutrition, healthy, good flavor and wide application range, can be used in the food heating or baking industry, and can endure the high temperature of 180DEG C-200DEG C for more than 10 minutes.