We have performed a series of molecular dynamics simulations to study the thermal decomposition characteristics of the non-cross linked cruing epoxy resin and the evolution of small molecules at different conditions using ReaxFF reactive force field, which bridges quantum mechanical and molecular mechanical methods. Reaction systems with 1620 atoms were simulated at various heating rates and temperatures from 2300 to 4300 K. We also discuss the relevance of our simulation results to previous experimental observations. The results show that the cleavages of nitrogen- and oxygen-bridge bonds are initiation reactions. Four primary formation pathways of H2O were observed, all of these reaction pathways involved hydroxyl-containing precursors. We found that at lower temperatures the primary product is H2O, whereas H2 is dominant one and the larger carbon cluster containing graphene-related structure prefers to formation at high temperatures. We also found multiple pathways leading to formation of H2, including intra- and inter-molecular dehydrogenation and hydrogen abstraction by hydrogen radical. Other small molecular products also found include CH4, HCN, NH3 and CO, but with an insignificant content of CO2. The formation of CH4 involves the demethylation of methyl group-containing precursor, which could evolve from methylene groups via hydrogen abstraction reaction. And the formation of CO involves the decar- bonylation of carbonyl group-containing precursor, which could evolve from ether oxygen group-containing fragments and hydroxy group-containing fragments via dehydrogenation reactions. Furthermost, the primary reaction products and the observed carbon clusters containing graphene-related structure were in accordance with experimental results. In our simulations, we find that these ReaxFF-MD simulations successfully reproduce thermal decomposition processes of depolymerization, chain reaction, defunctionalization, ring formation and polycondensation of the fragments observed in various experimental studies. The agreement of these results with available experimental observations demonstrates that ReaxFF can provide useful insights into the complicated bulk thermal decomposition of organic materials under extreme conditions at the atomistic level.%采用ReaxFF动力学方法模拟了非交联固化环氧树脂在不同温度和升温速率下的热解特性．结果表明，含N和含O桥键的断裂是热解的引发反应．观察到H2O的4种主要的生成途径，而这些反应途径都涉及到含羟基的前驱体．当反应温度较低时，H2O为热解的主要产物．而在高温条件下，热解的主要产物为H2，它主要为分子内／分子间脱氢反应和氢自由基的夺氢反应的产物：高温同时促进了含石墨烯结构且分子量较大的碳团簇的形成．除此之外，还观察到了CH4，HCN，NH3和CO等小分子产物．本文用ReaxFF动力学方法模拟所得的气体产物以及含类似石墨烯结构的碳团簇与实际实验结果一致，说明ReaxFF动力学方法能为从分子水平上研究有机物高温热解反应提供了一种有效的途径．
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