An embodiment of the invention provides a method and a device for judging the types of internal defects of gas-insulated combined electric appliances. The method includes acquiring internal gas samples of the gas-insulated combined electric appliances filled with sulfur hexafluoride gas; analyzing the molar concentration of decomposition gas of sulfur hexafluoride in the internal gas samples and determining the types of the internal discharge defects of the gas-insulated combined electric appliances according to the molar concentration of the decomposition gas of the sulfur hexafluoride in the internal gas samples. The decomposition gas of the sulfur hexafluoride comprises sulfur dioxide, hydrogen sulfide, carbon dioxide, carbon monoxide, carbon tetrafluoride, thionyl fluoride and sulfonyl fluoride. According to the scheme, the method and the device have the advantages that diversified stable decomposition products generated in internal partial discharge procedures of the gas-insulated combined electric appliances are integrated with one another, information of procedures of physiochemical reaction such as oxidation and hydrolysis in SF6 gas decomposition procedures is implied, the method and the device are scientific and systematic, diagnosis bases can be provided for reliably operating the gas-insulated combined electric appliances, and the accuracy and the judging efficiency can be advantageously improved.