Abstract: In Re-Os isotope chronology, the acetone extraction process is quicker and easier compared to the anion exchange method. The Re solution which was separated and purified by acetone extraction is suitable for the measurement by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS), but unsuitable for Negative Thermal Ionization Mass Spectrometry (N-TIMS) directly because of high salt contents. An improvement was made to the acetone extraction method to separate and purify Re for N-TIMS determination by increasing the alkalinity concentration from 5 mol/L to 10 mol/L. Compared with the anion exchange method, the acetone extraction process is not only easier to operate with lower blank (Re 3-7 pg), but also saves time. The signal intensity of Re was over 100 mV per 1 ng Re, which met the requirements of a high-accuracy instrument measurement completely. The national first grade standard material of JDC (GBW 04436) and the laboratory reference material of JCBY were measured to verify the improved method. The Re contents of JDC and JCBY obtained from this method were (17.17±0.50) μg/g and (38.34±0.44) ng/g, respectively, which were consistent with the certified value of JDC (17.39±0.32) μg/g and the certified value of JCBY (38.61±0.86) ng/g. The improved procedure was applied to practical samples with good long-term results.