A method of curve smoothing for self calibration data processing in the inertial platform was proposed in this paper.The appropriate curve smoothing criterion was given according to the characters of self calibration data. The outlier elimination and replacing algorithm was proposed through analyzing the influence of outlier on the curvature, and an algorithm for outlier choosing was proposed.An algorithm of the second difference quotients reference value was obtained by connecting the least square with the B spline, so the modified value for the outlier was gotten through seeking the minimum distance between the actual the second difference quotients and the reference value.The experimental results indicated that,the algorithm could well solve the problem of outlier elimination in the inertial platform self calibration data.The accuracy of curve smoothing could be controlled through adjusting the parameter,and the method had the feature of simple algorithm and convenient to use.