The invention relates to a permanently antistatic polyamide 66 / polypropylene (PA66 / PP) alloy, and a preparation method thereof. The material comprises the following components in percentage by weight: 3 to 8 percent of antistatic masterbatch, 40 to 43 percent of PA66, 40 to 52 percent of PP and 1 to 5 percent of compatilizer, wherein the masterbatch comprises the following components in percentage by weight: 1 to 15 percent of alkali metal salt, 0.1 to 2 percent of antioxidant, 0.1 to 2 percent of heat stabilizer, 0 to 10 percent of antistatic aid and 70 to 95 percent of polymer material containing a polyether block. The preparation method comprises the following steps of: weighing raw materials in the weight proportion, mixing, discharging, and performing extrusion granulation. The alloy has the advantages of good and durable antistatic effect, high comprehensive mechanical property, low cost, high heat resistance and the like, and achieves a permanent antistatic effect, the performance of the alloy is close to that of a pure PA66 / PP alloy, and the color of the alloy is light and can be prepared into various colors. The surface resistivity of the permanently antistatic PA66 / PP alloy can reach 106 to 108ohm.m.