The invention provides an OLED driving film transistor parameter obtaining method. The OLED driving film transistor parameter obtaining method comprises steps of using a data line to provide different first gate voltage, second gate voltage, third gate voltage and fourth gate voltage, using a sensing unit at a gate of a second film transistor to write the first gate voltage, the second gate voltage, the third gate voltage and the fourth gate voltage, wherein the source electrode of the second film transistor detects driving current flowing through a second film transistor and a third film transistor when a conducted third film transistor, a lead and a switched-off switch are connected to reference voltage, calculating a drain source electrode step voltage of a third film transistor according to current flowing through the second film transistor and the third film transistor and obtaining source electrode voltage of a more accurate second film transistor which corresponds to the first gate voltage, the second gate voltage, the third gate voltage and the fourth gate voltage so as to obtain accurate parameters of the driving film transistor. As a result, compensation is performed on an OLED panel according to the parameters of the driving film transistor in order to improve image compensation uniformity.