The direct determination of sulfur isotope ratios 34S/32S (δ34S), in atmospheric precipitation by triple quadrupole inductively coupled plasma mass spectrometry (ICP-MS/MS) is challenging owing to intense interference from polyatomic species of mass that affects all sulfur isotopes. Additionally, high background levels of sulfur often pose a challenge for accurately determining δ34S at low concentrations in atmospheric precipitation samples. To address these challenges, a reliable method based on mass shift ICP-MS/MS was developed in this study. The δ34S ratio was determined at m/z 48 and 50 instead of at m/z 32 and 34 by using O2 as a reactive gas to shift the 32,34S+ ions to 32,34S16O+, thus avoiding on-mass interferences at m/z 32 and 34. The sulfur concentration in the background blank, which mainly originated from the Ar and O2 gas used during analysis, was reduced from 22.1 μg L–1 to 0.82 μg L–1 by purifying Ar and O2 using a gas trap. The δ34S measurements were not significantly affected by the sulfur concentration of the sample between 200 and 1000 μg L–1, and the atmospheric precipitation matrix did not affect δ34S determination using ICP-MS/MS. Therefore, the proposed method does not require strict matrix and concentration matching, simplifying the analytical process. The results obtained from atmospheric precipitation using the proposed method are consistent with those obtained by isotope ratio mass spectrometry, thereby validating the proposed method.