Two methods for preparing crystallised dintroglycoluril （DINGU） via.recrystallization from nitric acid or nitration of glycoluril in mixed acid of HNO3-H2SO4 were investigated. Various factors affecting the DINGU crystal size, such as concentra tion of nitric acid, nitration coefficient of mixed acid, temperature and time of stabilizing treatment, and stirring etc, were discussed. The result of DINGU crystal preparation from DMSO was described as well.