Embodiments of the present disclosure provide a thin film transistor (TFT) and a method of manufacturing the same, which enables to decrease the vertical resistance from the source and the drain to the polarity inversion region, so that the current from the source and the drain to the polarity inversion region may be increased, thereby improving the performances of the TFT. An active layer of the TFT is provided with a first groove and a second groove which neither pass through the active layer. A source and a drain of the TFT are formed at least partially in the first groove and the second groove, respectively. The source and the drain contact the active layer through the first groove and the second groove, respectively.