An electrospray ionization-high resolution mass spectrometric（ESI-HRMS） method was developed for the determination of thermolabile N,N-dimethylaminomethyl ferrocene compounds.The relative standard deviation（RSD，n=10） for the ion counts of the target molecule was 2.4%.By analysis of the MS spectrum and MS/MS spectrum of the target molecule，it is showed that an in-source dissociation of the target molecule took place with the abundance of the mother ion being less than 10% of the abundance of the main daughter ion in the MS spectrum.The relevance of ion counts of the target molecule and its main daughter ion with temperature of the drying gas and voltage of the capillary export（Fragmentor） were investigated，respectively.Furthermore，corresponding fitting mathematical equations were established，and the optimum analytical conditions of the target molecule by ESI-HRMS were obtained.