The present disclosure provides a thin film transistor, including a base substrate, an active layer and a source/drain, and a conductive layer. The active layer and an outer edge of the conductive layer are formed in the same etching process. The present disclosure further provides a method for manufacturing a thin film transistor, including forming an active material layer and a conductive material layer, forming a photoresist on the conductive material layer, exposing and developing the photoresist by means of a halftone mask, removing segments of the active material layer and the conductive material layer corresponding to a photoresist completely-removed region by a same etching process, partially removing the photoresist in a photoresist completely-retained region and completely removing the photoresist in a photoresist partially-retained region, and removing a segment of the conductive material layer corresponding to the photoresist partially-retained region.