The performance of high-gain linear active disturbance rejection control(LADRC) will be greatly affected and limited when the system output is polluted by noise. In terms of the problems of poor noise suppression and serious bandwidth loss in classical filtering algorithms, a control strategy is proposed to reduce the noise sensitivity of the LADRC by using the noise observer(NOB), and further increase the control bandwidth. Firstly, the frequency-domain characteristics and discretization effect of the LADRC are analyzed. The influence of sensing noise on the system bandwidth is analyzed as well. Then, the implementation of the LADRC based on the NOB is introduced, and the stability analysis of the system is carried out. Finally, the proposed method is verified in the position loop of the inertial reference unit, and compared with the low-pass filter and the predictive tracking differentiator. The simulation results indicate that the NOB can suppress the noise and simultaneously reduce the phase loss. Experimental results show that the LADRC based on NOB can reduce the RMSE of the driving signal to 20.47% and reduce the rise time of the system step response by 56.67% compared to the LADRC. The NOB is proved to be practical and efficient on reducing the noise sensitivity of the LADRC and improving the system bandwidth.