The disclosure discloses a thin film transistor and a manufacturing method thereof. The method includes depositing quantum dot ink containing carbon quantum dots in a groove region between a source electrode and a drain electrode, after the quantum dot ink is dry, cleaning and blow-drying the dried quantum dot ink to film the carbon quantum dots to be an active layer of the thin film transistor. Accordingly, the disclosure can simplify the manufacturing process of the thin film transistor and enhance the production efficiency, as well as reducing costs and improving control sensitivity.