An OLED display device is disclosed, which comprises: a TFT substrate, comprising a substrate and plural TFT units disposed on the substrate; and an OLED unit electrically connected to one of the plural TFT units. The TFT units respectively comprise: an active layer disposed on the substrate and made of polysilicon; a first insulating layer disposed on the active layer; source and drain electrodes disposed on the first insulating layer; a metal layer disposed on the first insulating layer; and a second insulating layer disposed on the metal layer, wherein the metal layer has plural first protrusions at a top surface thereof, the second insulating layer comprises a first region corresponding to the active layer and a second region corresponding to a region outside the active layer, and a roughness of a top surface of the first region is greater than that of the second region.