Abstract: The method of analyzing the silicon isotope ratios was developed by collision cell multi-collectors inductively coupled plasma mass spectrometry (MC-ICP-MS). Replacing to PFA nebulizer, Pt cones and sapphire injector were proved to be helpful to decrease the silicon concentration in the instrument; silicon ions were partly separated with interferences after， when the mass resolution was increased by adjusting the slits’ width; using mixture of Neon (Ne) and Argon (Ar) as collision gas and keeping the matrix(TMAH) in lower concentration could efficiently reduce the production of polyatomic ions, which contributed to the decrease of isobaric interferences. Subsequently, the silicon isotope composition of samples WASO 04 and GBW(E)080272 were determined, the uncertainty of this method was about 0.02%, the δ³⁰Si value of GBW(E) 080272 relative to WASO 04 was -1.57‰.