A series of high energy density compounds (HEDCs) based on N-nitrourea were designed and their theoretical performances were calculated using the Gaussian programs. The predicted values of the energy density of these compounds are in the range 1.848-1.93 gcm(-3), and their calculated VODs are in the range 6700-8305 ms(-1). Tetranitrodiglycoluril (TNDGU) (1) and tetranitrotriglycoluril (TNTGU) (2) were synthesized and characterized by NMR (H-1, C-13) and IR spectroscopy as well as elemental analyses. The structure of the aminolysis product (7) of TNDGU was further confirmed by single-crystal X-ray diffraction, which indicated that the structure belongs to P2(1)/c space group in the monoclinic system.