A non-linear error algorithm is proposed to achieve higher pointing accuracy for star sensors under carrier movement.The error sources of the star sensors are analyzed, and a linear error model of the measured vectors is established.Based on operating features of the star sensors and the sources of the nonlinear error, an improved nonlinear error algorithm is derived to eliminate all the pointing errors.An experiment is made taking a certain type of star sensor as an example.The experimental result shows that the algorithm can identify the errors more accurately and improve the performance of the star sensors.