A reviews with 31 referencess dealing with the progress and the application of Atmospheric Pressure Ionization/Time-of-flight mass spectrometry (API/TOFMS) is presented, with emphasis on the instrumental characterization using atmospheric pressure chemical ionization or electrospray ionization/TOFMS. API-TOFMS has wide mass measurement range (up to 25,000 m/z). Its detection limit is 3～11 amol. The use of orthogonal acceleration and reflectron technique overcome space disperse effect and energy disperse effect of ions. Thus the resolution of API-TOFMS (10,000 FWHM) is much higher than quadrupole mass spectrometer. In addition, Microchannel plate detector improves the analytical accuracy (5 ppm), and shortens the analytical time to 35 s. For the sake of microanalysis and the analysis of sample with complex background, microspray technique and antipollution design were developed. It is to note important to note that API-TOFMS can be very easy to be employed in connection with other mass spectrometer. Because of its great advantages, API-TOFMS may be applied in such areas as biological analysis or combinatorial chemistry. For example, it can sequence protein or DNA by CID and determine noncovalent complex. The causes of some diseases, e.g. cancer, can be explained at biological molecular level with the help of API-TOFMS. Moreover, it can analyse mixtures of some biological macromolecule substrate with the separate technique (e.g. CE).

Key words: ATMOSPHERIC PRESSURE, IONISE (=IONIZE), POLAR MOLECULE, IONIZATION, COMBINED ANALYTICAL INSTRUMENTS, TIME-OFF FLIGHT MASS SPECTROMETRY