The utility model relates to a power-frequency voltage-withstand testing device in an SF6 armored type. The power-frequency voltage-withstand testing device comprises a tank body (1), wherein a sample capacitor (2) is arranged in the tank body (1), the bottom part of the sample capacitor (2) is arranged on a mounting bottom plate (3), the mounting bottom plate (3) is arranged on a frame () through a hinge base (4), and the mounting bottom plate (3) is driven by a driving device (5) to rotate around the hinge base (4). The power-frequency voltage-withstand testing device increases the working efficiency of tests through the special arrangement of the capacitor mounting structure, and saves time and labor.