An apparatus for on-line monitoring particle contamination in special gas includes a single particle inductively coupled plasma mass spectrometry (sp-ICPMS) and a gas exchange device (GED). The gas exchange device is coupled to the sp-ICPMS. The gas exchange device includes a corrosion resistant outer tube and a polytetrafluoroethylene (PTFE) inner tube. A gap is formed between the corrosion resistant outer tube and the PTFE inner tube. The length of the PTFE inner tube is 1 meter or more. The argon gas flows in the gap, and the special gas flow in the PTFE inner tube.