Abstract: Fused silica hemispherical resonators (HSR) serve as the core component of hemispherical resonator gyroscopes, where surface integrity directly governs their vibration performance. However, during ultra-precision grinding, cracks and pits are easily generated, limiting further performance enhancement. The evolution of grinding-induced damage during magnetorheological finishing (MRF) and its influence on HSR performance were investigated through integration of ultra-precision grinding with MRF. Results show that with increasing MRF material removal, small-scale defects are progressively flattened, while large pits and deep cracks require multiple cycles for complete elimination. After the MRF process, the surface roughness (Sa) of the HSR was reduced to 0.003 μm, with roundness and coaxiality errors maintained within 0.26 μm. Performance tests revealed that the Q factors of ϕ30 mm and ϕ20 mm HSRs (prior to acid etching) increased markedly from 0.23 million and 0.18 million to 29.70 million and 21.00 million, respectively, while frequency splits decreased from 0.2−0.3 Hz to below 0.005 Hz. These findings reveal the evolution mechanism of grinding damage during MRF and confirm the critical role of surface integrity improvement in the high-performance manufacturing of HSRs.