Variance（or Allan variance） analysis method is widely used in the error test of ring laser gyro（RLG）.Various error sources are distinguished through regression of σ

2

（τ） at different sample time.The dada points by which σ

2

（τ） is calculated goes small when the sample time is very long

this makes bad precision of（σ

2

（τ））.If σ

2

（τ） at long sample time are not used

the data for the regression points becomes less

and this brings lower precision of fitting result.Weighted regression model is proposed to processe variant-precision problem in error test of RLG.