Taking N-tert-butyl-3,3-dinitroazetidinium nitrate (BDNAN) as precursor,1,3,3-trinitroazetidine(TNAZ) was synthesized by five different nitrolysis systems. The optimal nitrolysis system was NH₄NO₃/Ac₂O. At the same time,the reaction conditions were optimized, and the optimal reaction conditions are as follows: n(Ac₂O):n(BDNAN)=25:1, reaction temperature is 80 ℃ and yield is 83.1%. The thermal characteristics and the split mechanism of TNAZ were studied. Results show that TNAZ having a stable four-membered ring skeleton melts at 99.5 ℃ with decomposition at 264.68 ℃.