Abstract: This paper reported the analytical results of the NIST SRM987 measured by Neptune multiple collector inductively coupled plasma mass spectrometry(MC-ICP-MS) over last two years.Geological samples after traditional chemical separation were measured by Neptune MC-ICP-MS and thermal ionization mass spectrometry(TIMS),respectively.Neptune MC-ICP-MS can precisely measure strontium isotopic composition as the TIMS does,even more effective and less time-consuming than the TIMS method.For the krypton from ICP source carrier—the argon gas,isobaric interference can be directly corrected without the requirement for mass discrimination correction due to low level of the krypton ion beam.As for the sample containing small amount of rubidium(Rb/Sr<0.01),direct calibration for isobaric interference and mass discrimination by the exponential law can be obtained by assuming that rubidium mass discrimination is the same as that of strontium.