Abstract: Radionuclide ⁹⁰Y is an important β-ray emitter for therapeutic applications and the accurate determination of the halflife of ⁹⁰Y is of great significance to theoretical research and practical application. At present, the halflife of ⁹⁰Y has been reported in a large number of literatures, but the results are not accurate, ranging from 63.46 h to 64.6 h. In this paper, the principles and processes of half-life measurement of ⁹⁰Y by liquid scintillation spectrometer (LSC) was introduced, and the uncertainty of the half-life value was gived. After separated by bis-2-ethylhexyl-phosphoric acid (HDEHP), the half-life of ⁹⁰Y was determined using a series of measurements performed with LSC. The measured halflife of ⁹⁰Y is 64.05 h and the uncertainty is 0.017%. The average value of our results is in agreement with the values published. The method is practicable and simple which deserves further promotion.