The invention relates to a laser pulse modulation device based on CrOCl crystal, and an application thereof in an all-solid-state laser. The CrOCl laser pulse modulation device is prepared by the CrOCl crystal. The all-solid-state laser of the CrOCl laser pulse modulation device comprises the CrOCl laser pulse modulation device. The CrOCl crystal is used for the CrOCl laser pulse modulation device, thereby achieving the following advantages: (1), Cr3+ ions are base ions in the CrOCl crystal, are high in concentration and are uniform in distribution, and the saturable absorption effect has high effectiveness and uniformity; (2), the working band is wide, the short-wave cutoff edge of the CrOCl crystal is located at 600 microns, the long-wave cutoff edge is located 18mm, and the saturable absorption can be achieved in the band from 600 microns to 18 mm; (3), the device is easy to prepare, can employ a gas-phase transmission method for growth, is high in yield, is large in size, is easy to peel, is smooth in surface, can be directly used for the laser pulse modulation, and is greatly convenient for production and manchining.