2,4,7,9-tetrazabicyclo ［4.3.0］ nonanone was prepared from ethylenediamine,glyoxal and urea by Mannich reaction. In this article, the factors which affect the synthesis reaction such as reaction time,reaction temperature and pH value were studied. The yield of 2,4,7,9-tetrazabicyclo ［4.3.0］nonanone was increased from 42% to 76.1% by changing the addition order of reagents,controlling the reaction time and the reaction temperature.