The electrical breakdown of camellia seed vegetable insulating oil and mineral insulating oil transformer is simulated in experiments, respectively. The dissolved gas characteristics of two kinds of insulating oil are studied by means of dissolved gas analysis method. The type and percentage of gas produced by oil paper breakdown of the two kinds of insulating oil are analyzed and compared. Results show that the two insulating oils produce seven characteristic gases, i.e. H₂, CH₄, C₂H₄, C₂H₆, C₂H₂, CO and CO₂, under the typical electrical faults. The total amount of gas produced in camellia-seed vegetable insulating oil increases with the increase of the times of breakdown, and the content of CO and CO₂ produced by the insulating oil of camellia seed vegetable is greater than that of mineral insulating oil. The percentage of C₂H₂ is always the highest, which shows that C₂H₂ is the main characteristic gas of camellia-seed vegetable insulating oil breakdown.