Abstract: A new surface desorption atmospheric chemical ionization mass spectrometry (SDAPCI-MS) method was established to directly fingerprint various tea products with neither sample pre-treatment nor toxic chemical contamination.Four tea products,LuShanYunWu,TieGuanYin,QiMenHongCha,and PuErCha,were successfully analyzed based on their unique mass spectral fingerprints.The identification of the molecular structure of interested ions was demonstrated by multiple-stage SDAPCI mass spectrometry.The SDAPCI spectral fingerprints of the four tea products did not change significantly after they were stored for three months at room temperature.The analysis time was less than 1 s for any single sample,and SDAPCI-MS can be operated online continuously.Clearly,SDAPCI-MS with water vapor in the atmosphere as ionization reagent can detect both volatile and non-volatile chemicals from tea product surfaces at ambient pressure,showing its potential in fast and nondestructive analysis of bulk samples.