Laser tracker distance measurement accuracy depends on the accuracy of laser Interferometer Measurement(IFM) and Laser Absolute Distance measurement (ADM). Based on the current technology, IFM measurement accuracy is much higher than ADM measurement accuracy. So the ADM measurement error needs to be compensated in order to improve laser tracker measurement accuracy. The compensation method of cubic spline function and linear function is compared and analyzed. The results show that the residual error of cubic spline function compasation method is 0.007 mm, which is much better than that of linear function method (0.029 mm). The verification points also show the same result. The conclusion is drawn that cubic spline function can be used to better correct ADM error of laser tracker.