Recently,the CnF_2nO species have received much attention in the field of alternative gases,particularly C_5F_(10)O and C_6F_(12)O,both of which have a very low global warming potential(GWP)and excellent insulation properties.Due to its excellent insulation performance,foreign scientific research institutions and companies begin to study the material and its mixture,and there are few studies on its decomposition characteristics under discharge.In this paper,based on the density functional theory,the stability of C_5F_(10)O and its possible decomposition path were analyzed.At first,the ionization energy of C_5F_(10)O was calculated,and the possible position of the reaction in the molecular structure was determined based on the frontier molecular orbital theory.Secondly,the possible decomposition pathway of C_5F_(10)O,the formation mechanism of the decomposition products and the corresponding energy changes were analyzed.Finally,the C_5F_(10)O/N_2 gas mixture was tested by using gas insulated test platform,the gas components in the gas chamber before and after breakdown were analyzed based on gas chromatography mass spectrometry(GC-MS),the insulation properties of the decomposition products and the dynamic equilibrium processes of various particles during the discharge process were discussed.The results show that the formation of CF_3CO·,C_3F_7·or C_3F_7CO·,CF_3·radicals is most likely to occur during the decomposition of C_5F_(10)O,and further reactions of various free radicals will generate CF_4,C_2F_6,C_3F_8,C_3F_6,C_4F_(10),C_5F_(12),C_6F_(14).The products have strong insulating properties,and the dynamic equilibrium between C_5F_(10)O molecules and free radicals exists,both of which ensure the insulation performance of the system.The test results showed that with the increase of breakdown times,the content of C_5F_(10)O decomposition products increased,and the growth rate of CF_4,C_2F_6 and C_4F_(10) was higher than that of C_3F_8 and C_6F_(14).The conclusions provide theoretical basis for further research of insulation properties and synergistic effect of C_5F_(10)O gas mixture,and provide a reference for the study of CnF_2nO environmentalfriendly medium.