Aiming at the problem that north-seeking startup error of fiber-optic gyroscope（ FOG） results in reducing of north-seeking precision

through numerical simulation analysis

characteristics of the north-seeking startup error of FOG are summarized

and the relationships between the error and the drift rate and azimuth angle are obtained. On the basis of traditional four-position north-seeking method

an improved four-position northseeking method is proposed

which can restrain the north-seeking startup error of FOG. North-seeking tests are carried out

the results show that the first north-seeking error of the new method decrease 80 % compared with the traditional method

which basically eliminates north-seeking startup error of FOG and significantly improves the north-seeking precision of FOG.