The invention discloses a novel method for improving the fatigue performance of magnesium alloy lubricating oil. The novel method for improving the fatigue performance of the magnesium alloy lubricating oil is characterized by comprising the steps that magnesium alloy is made into a sample which can be clamped easily by the fatigue tester; the tension-compression cyclic stress load under the yield limit is preloaded on the sample through the fatigue tester at the room temperature of 25 DEG C, and after preloading, the sample is placed in lubricating oil containing nanometer grade blast furnace titanium slag as an additive; and after soaking for 2-4 hours, the sample is removed and the surface of the sample is degreased, and treatment of the magnesium alloy sample is finished. According to the novel method for improving the fatigue performance of the magnesium alloy lubricating oil, the technique that low stress cyclic preloading is combined with surface repairing of nanometer materials is adopted, the magnesium alloy grains can be refined, the fatigue strength of the material is improved, and defects or uneven areas of the surface of the magnesium alloy material are repaired through the titanium slag of nanometer grade blast furnace so that the corrosion of magnesium alloy material under the condition of lubricating oil can be effectively reduced or prevented, and the fatigue performance of magnesium alloy material under the condition of lubricating oil is greatly improved.