A method for high_precision measurement of Zn isotope composition has been estab lished，which includes correction of instrumental mass discrimination, assessment of isobaric interferences, investigation of matrix effect, and exami nation of long-term repeatability.It has been shown that the instrumental mass discrimination can be corrected with the standard-sample-bracketing method. Theassessment of isobaric interferences was carried out using three approaches, i.e ., ① the direct measurement of the interference signals in the high-resolution mode; ② the examination of correlation between Zn isotope ratios of the raw dat a in a low-resolution mode; ③ the investigation of the deviation of the measured Zn isotope values relative to the “real value". The matrix effect was examined by using the mixed solution of Fe and Zn relative to pure Zn solution. It is found that the content of Fe has no detectable effect on the measured values of Zn isotope when the Fe/Zn ratio is lower than or equal to 0.2.The repeatability as sessed over a period of 7 months is better than 0.06‰ (2sd) per amu. The Zn iso tope composition of a national standard reference material of sphalerite (GBW 7270) was analyzed with the techniques established, and the results are δ66Zn =6.71‰±0.03‰( 2σ)δ67Zn = 10.08‰±0.05‰(2σ)，andδ68Zn=13.37‰±.07‰(2σ).