A method of manufacturing a transistor display panel and a transistor display panel, the method including forming a polycrystalline silicon layer on a substrate; forming an active layer by patterning the polycrystalline silicon layer; forming a first insulating layer covering the substrate and the active layer; exposing the active layer by polishing the first insulating layer using a polishing apparatus; and forming a second insulating layer that contacts the first insulating layer and the active layer, wherein exposing the active layer by polishing the first insulating layer includes coating a first slurry on a surface of the first insulating layer, the first slurry reducing a polishing rate of the active layer.