The invention relates to a compact enclosed gas-insulated DC high voltage generator which comprises an insulated enclosed casing, a charging circuit, a voltage multiplying circuit and a resistance voltage divider, wherein the charging circuit, the voltage multiplying circuit and the resistance voltage divider are mounted in the casing and electrically connected via leads. A support insulating cylinder is arranged at the middle position in the casing, the charging circuit is fixed at one end of the support insulating cylinder, the voltage multiplying circuit is fixed at the two side surfaces and the upper surface of the support insulating cylinder, and the resistance voltage divider is fixed to the lower surface of the support insulating cylinder in parallel. The DC high voltage generator can effectively reduce the size and weight, the insulation performance of the generator is improved, and and the generator is suitable for onsite test and DC high voltage test of ultrahigh tension transformation equipment.