The invention provides a dielectric property test device, which comprises a base, a slide rail, a fixation wall, a press wall, a pair of rotation walls and a cover body. The base has a first detection surface. The slide rail is arranged on the first detection surface along the extension direction thereof. The fixation wall is fixedly arranged on the first detection surface, and the fixation wall has a second detection surface. The press wall has a third detection surface; and the press wall is slidably arranged on the slide rail and enables the third detection surface to be able to move facing to the second detection surface. Each rotation wall is rotatably arranged on the base; and each rotation wall has a fourth detection surface. Each fourth detection surface can rotate to a rotation position with each rotation wall. The two fourth detection surfaces in the detection positions are arranged face to face, and can form an accommodation space with the first detection surface, the second detection surface and the third detection surface. The cover body can seal the accommodation space, and the cover body has a fifth detection surface facing the accommodation space. The dielectric property test device also comprises a metal foil layer covering the first detection surface, the second detection surface, the third detection surface, the fourth detection surface and the fifth detection surface.