Accordingtothedefectdetectionofhigh-reflection mirrorusedinsquarelasergyro，thephenomenonthatthere is a blind area in the detection of micrometer-level scratch-shaped defects when using a laser light source is analyzed. In practical use，the defect detection is the same as the incident angle of the light source when the gyro is used，a laser light source is incident on the high-reflection mirror at an angle of 45°，scattered light from defects is imaged on CCD through microscopic imaging light path，the imaging situation of micrometer-level scratch-shaped defects is discussed based on experimental data. A novel laser lighting method is proposed，the light source is designed as a full light curtain lighting mode without dead angle within 180°. The detection blind area of a single laser source illumination is overcome. The measurement error caused by the motion control is avoided. The image processing steps are simplified. The detection efficiencyandaccuracyareimproved.