The invention provides a preparation method of functional brown sugar. The preparation method includes: step 1, dissolving white granulated sugar in water at 60-90 DEG C, and heating to 120-140 DEG C to obtain syrup; step 2, mixing the syrup at constant temperature till sugar grains occur, sequentially adding brown sugar and accessories, continuing mixing for 8-12 minutes, allowing for standing and cooling to 90-110 DEG C to obtain primary mixed syrup; step 3, mixing the primary mixed syrup at constant temperature for 1-5 minutes, allowing for standing and cooling to 70-90 DEG C to obtain semi-finished mixed syrup; and step 4, mixing and cooling the semi-finished mixed syrup to obtain the functional brown sugar. The invention further provides ginger grown sugar produced by the preparation method. The preparation method of the functional brown sugar is simple in process, convenient to operate and suitable for industrial production. The ginger brown sugar produced by the preparation method is simple to produce, tastes sweet and spicy and has bright color, moderate thickness and fragrance, a formula of the ginger brown sugar is reasonable, materials of the ginger brown sugar are low in price, the ginger brown sugar is nutritious and can effectively prevent colds and relieve cold symptoms.