Abstract: In thes paper Energy Resolved Mass Spectra (ERMS) of four pairs E, Z-isomers of tetradecenols have been studied through chemical ionization with methane as the reagent gas on triple quadrupole mass spectrometer. Both chemical ionization mass spectra of there isomers and collision activatde decomposition of their quasi-moleculal ions (M-H). with Ar as collision gas are very similar. However, the differences of ERMS are enough to differentiate the E,Z-isomers. The reasons Which leads to there differences are discussed.