Abstract: Based on two-dimensional metallographic microscopic measurement technology, the damage area and morphology of the silicon-based quadrant photo-detector(QPD) were studied under different laser energy fluences and pulse widths. The damage area and morphology of silicon-based QPD with single cell change with laser energy fluences and pulse width were measured. The results showed that, the QPD produced surface pooling, folding, cracks, ablation areas and other damage effects under the action of a millisecond pulse laser. The damage area mainly affected by the incident laser energy fluences, and the damage area gradually increased with the laser energy fluences and decreased with the increase of pulse width. The damage thresholds of a silicon-based QPD with different laser pulse widths were obtained. At 0.5 ms, and the energy fluences was 15.79 J/cm², the silicon-based QPD produced melting damage, and the energy fluences values of surface-damaged thresholds in the silicon-based QPD with pulse widths of 1.0, 1.5, 2.0 and 3.0 ms are 14.12 J/cm², 33.94 J/cm², 39.76 J/cm² and 47.62 J/cm².