The lock-in effect is the main source of error in laser gyroscopes.In order to reduce the lock-in threshold,Based on the self-consistent equations of the laser gyro,this paper derives the thresho ld formula of the locked state lock-in.The lamb coefficient under the third-or der perturbation is analyzed by MATLAB software,and the influence of laser oscil lation frequency,backscatter angle and relative excitation degree on the thresho ld of lock-in is studied.The results show that Laser gyroscope with a cavity le ngth of 0.28m which the lock-in threshold is not symmetrically distributed abo ut the center frequency,nor does it strictly decrease with the increase of the b ackscatter angle.There is a frequency range on both sides of the center frequenc y.The lock-in threshold will increase to a maximum with the increase of the bac kscatter angle,and then decrease with the increase of the backscatter angle.In t he other frequency range,the lock-in threshold decreases to a minimum with the increase of the backscatter angle,and then increases with the increase of the ba ckscatter angle.Through comparative analysis,it is obtained that when the freque ncy parameter is 28.14MHz and the backscatter angle is 89°,the lock-in thresh old is the smallest.By increasing the excitation to 1.5,the lock-in threshold c an be reduced to 0.034°/h.