In the field of small unmanned helicopter, strapdown inertial navigation system (SINS) of laser gyro is not only used for navigation, but also used for flight attitude control. The requirement of navigation accuracy and real-time capability of laser gyro SINS is higher. But the traditional high-order FIR low pass filter to laser gyro IMU signals has a large time delay, so that the filter is difficult to satisfy the system. In order to take care of the measurement accuracy and response time, a filter method that combined LMS adaptive notch filter and low-order FIR low pass filter is studied, and the IIR narrowband filter is introduced in order to solve the acquisition problem of the dither frequency reference signal. Theoretical analysis and test results show that the method can not only effectively eliminate the impact of the dither offset frequency signal and the outside world high frequency noise, but also can significantly reduce delay time to 2 ms. It has very high engineering practical value.