A thin film transistor, a manufacturing method thereof, and a display device are provided. The thin film transistor includes a gate electrode (21), an active layer (23), a source electrode (241) and a drain electrode (242). The source electrode (241) and the drain electrode (242) are formed of at least two materials, the forming materials of the source electrode (241) and the drain electrode (242) can create a cell reaction in a corresponding etching solution so as to be etched, and material of the active layer (23) is not corroded by the etching solution. With the thin film transistor and manufacturing method thereof according to embodiments of the invention, a problem that an active layer is liable to be corroded in an etching procedure of a source electrode and a drain electrode can be solved, and thus the thin film transistor device can be manufactured by using a back channel etch process. Consequently, the process number for manufacture of the thin film transistor is decreased, and the manufacturing cost is saved.