Abstract: A method for analysis of dihardenedtallowdimethyl ammonium compounds (DHTDMAC) was established by high performance liquid chromatography-electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS). The mass spectrometric fragmentation mechanism of DHTDMAC was analyzed based on the information of characteristic parent ions and daughter ions, which were obtained from ESI and tandem mass spectrometry. Sixteen components of DHTDMAC were deduced. The components and fragmentation mechanism of DHTDMAC were verified by neutral loss mass scanning, parent ions scanning and daughter ions scanning. As the chromatography conditions were optimized, the analysis of the target compounds was performed under electrospray positive ion source and multiple reaction monitoring mode (MRM). This study identified different alkyl chain lengths and carbon numbers of dihardenedtallowdimethyl ammonium compounds. The method was simple and fast， which was established to detect different component of DHTDMAC. It can provide testing basis for the kind of compounds in environment, chemical products and consumer products, etc, which is helpful for the in-depth research and quality control of DHTDMAC.