The invention relates to a direct current gas insulation electrical equipment partial discharge decomposition simulation experiment apparatus and belongs to the technical field of direct current gas insulation electrical equipment insulation state on-line monitoring. The direct current gas insulation electrical equipment partial discharge decomposition simulation experiment apparatus comprises a direct current power supply system, a gas discharge enclosed air chamber, a detection system and a typical insulation defect physical model, wherein the direct current power supply system comprises a voltage regulation console, a test transformer, a protection resistor, a capacitive voltage divider and a high voltage rectification silicon stack lamp; the detection system comprises a pulse current detection system and a gas chromatography-mass spectrometry detection system; and the typical insulation defect physical model comprises a metal protrusion insulation defect model, a free metal particle insulation defect model, an insulator metal pollution insulation defect model, an insulator air gap insulation defect model and the like. The invention can effectively simulate a typical insulation PD fault and the decomposition process of SF6 under the action of a typical insulation defect PD in direct current gas insulation electrical equipment, thereby providing a solid basis for a system to research direct current PD characteristics, SF6 direct current PD decomposition characteristics and decomposition theories. The invention can be widely used for simulating direct current gas insulation electrical equipment partial discharge.