Abstract: Single-axial rotation can compensate the vertical errors of the inertial apparatus automatically, but can not compensate the axial vertical errors in inertial navigation system. Therefore, the axial drift of ring laser gyroscope (RLG) is an important factor for affecting the accuracy of inertial navigation system. The accurate identification of axial RLG drift can improve the precision of inertial navigation system. The identification model of axial RLG drift based on artificial fish swarm algorithm (AFSA) was introduced and the steps and method were given. The experimental results show the identification model by AFSA is accurate and the drift instability of RLG after it is compensated is 0.000 4 /h. The proposed method is an effective approach and has a better identification precision and engineering practice value.