Mass imbalance in hemispherical resonators—caused by asymmetric defects introduced during manufacturing and assembly processes such as material anisotropy, machining inaccuracies, and assembly misalignments—leads to non-ideal vibration modes. These imperfections result in quadrant-wave standing wave distortion, intensify Coriolis effect coupling errors, and ultimately degrade the output performance and navigation accuracy of hemispherical resonator gyroscopes (HRGs). To tackle this key challenge limiting the development and large-scale production of high-precision HRGs, this study introduces an identification method that combines virtual rotation state parameter demodulation of standing waves with support-beam vibration detection. Laser vibrometry is employed to precisely capture the resonator’s vibration characteristics, enabling quantitative characterization of mass imbalance. A systematic investigation reveals how precision forming, metallization coating, and high-accuracy assembly each impact the mass distribution, highlighting the correlation between process-induced errors and vibration mode coupling. Based on these insights, a hierarchical balancing strategy is proposed. To implement it, an automated balancing system is developed, integrating standing wave control, vibration measurement, and micro-material removal technologies. Experimental validation shows that after balancing, the 4th harmonic frequency split is reduced to 0.056 mHz, and the coupling vibration amplitudes of the 1st-3rd harmonics are kept below 0.03 nm, given a 4th harmonic amplitude of 0.15 μm. These results verify the effectiveness and precision of the proposed balancing method, offering strong technical support for the advancement and mass production of high-precision HRGs