Abstract: A Study on Mass Spectra of Organophasphorous Compounds(XⅢ). The EIMS of 1, 3, 2-Diazaphospholidin-4-one DerivativesSong Fengrui;Liu Shuying(Changchun Institute of Applied Chemistry, Chinese Academy of Sciences,Changchun 130022, China)Li Chenxi;Chen Ruyu(Institute of Element Organic Chemistry, Nankai University,Tianjin 300071, China)Abstract:The electron impact mass spectra of nine new phosphorus-containing heterocyclic compounds were reported. The general fragmentation mechanisms and mass spectral behaviors were studied by using high resolution precise mass determination and linked scan techniques. Some skeleton rearrangement reactions and the ring-opening reactions were discussed in detail.Keywords: EIMS, phosphorus-containing heterocyclic compounds, rearrangement reaction, ring-opening cleavage