Recombinant human parathyroid hormone (PTH) (1-34) was identified by new technique nano-electrospray ionization (ESI)-quadrupole-time of flight (TOF) tandem mass spectrometry. The measured molecular weight of PTH(1-34) was 4115.21 by ESI-mass spectrometry (MS) and measurement percent error was only 0.06 %. Digested PTH(1-34) by trypsin at 37℃ over night. The tryptic digested peptides were measured and then four charged peptides were selected to determine amino acid sequence by MS/MS. Then their sequences were interpreted from a,b,y series ions of peptides by the collision-induced-dissociation (CID) in the product ion mode. The sequence of peptide m/z 728.4 measured by MS/MS was VSEIQLMHNLGK. And all peptides sequences and database search results were both PTH (1-34) . The study proves that the primary structure of recombinant PTH (1-34) is correct .There is no amino acid deleted, mutated and modified in its expression and purification. It also shows that nanoESI-MS/MS is a good method to identify protein and acquire integrated sequence information with advantage of sensitivity, high speed and accuracy.