The invention discloses a drilling shaft pressure calibrating method. The method comprises the following steps: measuring bottom hole pressure by using a down hole pressure measurement-while-drilling tool; calculating predicted bottom hole pressure; calibrating drilling shaft pressure according to the measured bottom hole pressure and the predicted bottom hole pressure to realize managed pressure drilling. According to the drilling shaft pressure calibrating method, the defect that errors between the drilling shaft pressure calculated and processed by a method in the prior art and actual down hole pressure are larger is overcome, and the drilling shaft pressure can be calculated in real time more quickly and accurately, so that the dynamic shaft pressure of a narrow-density window stratum can be accurately calculated and can be calibrated and controlled in real time, good control requirements on the bottom hole pressure are met, and requirements on safe and quick drilling are guaranteed.