Aiming at the error coefficients of IFOG are not stable and vary with time slowly in rotary strapdown inertial navigation system, a novel calibration method which utilizing the six-position is proposed in this paper. According to the error model of IFOG, the error parameters of IFOG, such as scale factor, installation error and zero drift, can be calculated through the six-position calibration path which is proposed by two-axis indexing. Coupling errors between the scale factor and the misalignment can be avoided by this method. The calibration precision which is caused by the indexing error is analyzed, and the principle of the novel calibration is validated by the rotary SINS navigation experiment. The result show that, the position accuracy using the proposed method is higher than the traditional one.