A novel allylphenoxytriazine monomer, 2,4-di (2-allylphenoxy)-6-N,N-dimethylamino-1,3,5-triazine (DAPDMT) was prepared in one-pot by reacting cyanuric chloride with 2-allylphenol at first, and then by directly treating the adduct with N,N-dimethylamine without separation. The monomer was used to modify a popular commercial bismaleimide (BMI) resin, 4,4'-bismaleimidodiphenyl methane (BMDPM), and the results showed that the monomer could effectively improve mechanical properties of BMDPM resin without greatly decreasing heat resistance of the resin. The better results were obtained when the molar ratio of DAPDMT/BMDPM was 1 : 4. Because of more reactive sites in the monomer, the potential uses of the monomer were predicted.