Abstract: Relative inclination measurement based on natural gamma imaging is an important technology in modern geo-steering. Currently, plenty of studies on improving the accuracy of natural gamma imaging ignore the distortion in measurement when the imaging instrument is rotating. This leads to an uncorrectable error incalculation of the relative inclination, interfering with the judgment of engineers. Based on numerical analysis technology, a study has been carried out to solve the problem ofdistortion in rotational measurement. This paper describes the phenomenon of distortion caused by the rotational natural gamma imaging instrument in the simulated wellbore experiment, explains the reason for this phenomenon theoretically, and then analyzes the serious influence of this phenomenon on the imaging accuracy and calculation of inclination. Taking the 8-sector natural gamma imaging instrument as an example, this paper derives a rotating sector algorithm, and in combination with the numerical analysis technology and the particle swarm algorithm, solves the problem of distortion and improve the accuracy of the algorithm, respectively. Finally, this paper presents the experimental results of the algorithm applied to the test device of the simulated wellbore in tilted formations. It can be seen that the rotating sector algorithm solves the problem of rotational distortion, thereby ensuring that the natural gamma imaging instrument can obtain the accurate relative inclination while drilling, thus providing a quantitative basis for the engineers to adjust the well trajectory.