The utility model relates to an insulating technical field that detects of direct current system is a portable DC insulation detection appearance testing arrangement, and it includes controller, display, variable resistance box, control switch and DC power supply, the output of controller is connected with the input of display electricity, variable resistance box includes box, positive power supply end, negative power source end is young and slide rheostat, be equipped with the electric wire hole on the lateral wall of box, the top of box is equipped with the opening, and slide rheostat second terminal is connected with negative power source end electricity, and control switch normally closed contact is connected with slide rheostat second terminal electricity, and control switch normally open contact is connected with the two -way electricity of controller. The utility model has the advantages of reasonable and compact structure, convenient to use, its gear through adjusting slide rheostat is realized carrying out the check -up to direct current insulation tester in advance, has improved the correct rate of the insulating alarm information of measuring of direct current system, has effectively got rid of the potential safety hazard.