Abstract: Stable chlorine and oxygen isotopic compositions of perchlorate can provide an important analytical tool for tracing sources as well as monitoring and evaluating its degradation pathways and remediation effects.In order to develop a new technique for the determination of stable chlorine and oxygen isotopic compositions of perchlorate,a vacuum isotope preparation system is established using a vacuum pyrolysis method,combined with a GasBenII-IRMS online measurement.The vacuum pyrolysis system showed high stability,with the best pyrolysis temperature of 650℃and a minimum amount of 10 μmol ClO^-₄.The analytical precisions of δ¹⁸O,Δ¹⁷O and δ³⁷Cl are 0.3‰,0.04‰ and 0.1‰,respectively,which is consistent with international level.This isotopic measurement can provide advanced means for prevention and remediation research on environmental contamination of perchlorate.