The present invention provides a thin film transistor (TFT) manufacturing method and a TFT, a source electrode or drain electrode of the TFT is electrically connected to a data line directly during a forming process by providing a through hole in a surface above the data line of the TFT, so as to save the process cost. Further, the source electrode and drain electrode of the TFT are also manufactured with poly-silicon rather than metal material used in prior art, processing steps are simplified, thereby further saving the process cost.