Abstract: Metal dust of micron level is often generated during the production and operation process of DC GIS/GIL, probably causing serious faults such as surface flashover of insulators. In this paper, a semi-closed coaxial cylindrical electrodes platform was built as to study the movement behavior and adsorption mechanism of the micro metal dust near the basin-type insulator, and unique phenomenon was obtained. Two adsorption modes of the metal dust was discovered, one is featured as "accumulative adsorption" moving towards the insulator surface, and the other is featured as "diffusive adsorption" moving towards the electrodes, meanwhile, "extreme value" phenomenon may appear with increase of the imposed voltage amplitude. The accumulative adsorption renders obvious polar effect, namely for the negative polarity case, the adsorption range is wider, the adsorption amount is larger and the completion time is shorter. The smaller the dust particle size is, the higher the adsorption lifting voltage will be, and the more likely a flashover will occur, what more, the increase in dust amount and imposed voltage may lead to "explosion" of the metal dust. Further, a stress analysis model under multi-physical fields was established to account for the experimental phenomenon. In the "V" shaped area formed by the insulator surface and the metal dust heap, the opposite effect of distorted electric field on the left and right sides almost offsets to the metal powder, hence,the principal influential factor on metal dust accumulative adsorption turns to be the coulomb force on the charged particles by the insulator surface charge, while the polarity of the insulator surface charge contributes directly to the polarity effect of accumulative adsorption. The main impacting factor on diffusive adsorption of mental dust lies in the distorted electric field stress on the far-away side of the charged dust pile from the insulator. The interaction between coulomb force and distorted electric field force causes the phenomenon of "extreme value" of accumulated adsorption. In addition, the prominent effect of inter-particle van der Waals force pays a key role, which can elucidate the facts that micron metal dust of smaller particle size manifests a higher adsorption start-up voltage.