The utility model belongs to the technical field of gas -insulated electrical equipment's state of insulation on -line monitoring, in particular to direct current gas -insulated electrical equipment partial discharge decomposes simulation experiment device. The utility model discloses a: a direct current system of exerting pressure: it is concrete including pressure regulating control cabinet, testing transformer, protection resistance, capacitive voltage divider, high -pressure rectification silicon stack, filter capacitance etc, a gas discharge room, a detecting system: including pulse current detecting system and gas chromatography -mass spectrometry detecting system, an insulating defect model: including metal projection, free metal particle, insulator metal contamination and four kind at least insulating defect model of insulator air gap. The utility model discloses can simulate direct current gas -insulated electrical equipment takes place PD under the insulating defect of typical case situation, can study SF6 direct current PD resolution characteristic, it is high to have a simulation degree of accuracy, device simple structure, advantage such as with low costs. The utility model discloses can extensively be used for direct current SF6 gas -insulated electrical equipment PD's simulation.