In the case of high-precision fiber optic inertial navigation systems (INS) after long-term storage, the error parameters of the fiber optic gyroscope and accelerometer tend to change. To address this issue, a rapid on-site self-calibration method for INS prior to launch was proposed, utilizing the dual-axis rotational inertial platform. This platform allowed the internal and external frame mechanisms to rotate independently. The method involved five rotations and the motion trajectories of six static positions (before and after rotation), which effectively excited the error parameters that were prone to change in the fiber optic INS. Furthermore, a calibration algorithm was proposed based on the variation curves of the horizontal velocity error increment at the two static positions before and after rotation. The first and second order terms of these curves were used as observation quantities. This method not only isolated the impact of frame mechanism oscillations on the calibration results but also eliminated the calibration errors caused by inaccurate modeling of misalignment angles after initial alignment. Simulation and experimental results demonstrate that the six-position method, as a rapid pre-launch calibration technique, is capable of calibrating the main inertial navigation error parameters with high precision and without reliance on external reference in just 18 min. In six physical experimental verification trials, the maximum relative error of the scale factor of the three-axis accelerometeris 4.88×10^-6, while the maximum root mean square error (RMSE) for the bias is 1.45×10^-4m/s². The maximum relative error of the scale factor of the three-axis gyroscope is 4.00×10^-6, and the maximum RMSE for the constant drift is 0.001 87°/h. These results satisfy the usage requirements for high-precision INS and provide an effective solution for improving the alignment and navigation accuracy of high-precision dual-axis rotational fiber optic INS.