用量子化学从头计算方法讨论了大气臭氧层主要破坏物之一ＣｌＯＮＯ２的存在，寻找到６１种可能的异构体，并在ＭＰ２／６－３１Ｇ＊级别比较了它们的能量，得出ＣｌＯＮＯ２（构型ａ）是较常见的稳定构型。研究了ＣｌＯＮＯ２在光照下最易发生的分解反应ＣｌＯＮＯ２→Ｃｌ＋ＮＯ３，寻找到反应过渡态ＴＳ１，并讨论了反应的可能历程。 Quantitative chemical ab initio method was used to discuss the existence of ClONO2, one of the major ozone depletors in the atmosphere. 61 possible isomers were found and their energies were compared at MP2 / 6-31G * level to obtain ClONO2 (configuration a) is the more common stable configuration. The decomposition reaction of ClONO2 → Cl + NO3, which is the most susceptible to ClONO2 under light irradiation, was investigated. The reaction transition state TS1 was found out and the possible reaction process was discussed.