The output characteristic of the traveling waves in the cavity is analyzed and it is found that the conventional lock-in control techniques have some disadvantages.The lock-in error discriminant signal is deduced from the equations for laser gyro.The high signal-to-noise ratio controlling means are implemented by the operation of beat frequency signal and cavity length signal.It is concluded that the approach is applicable to both constant biased and alternating biased laser gyro,and the the lock-in zone of laser gyro is precisely controlled in the operating temperature range.