In this paper, the Er∶ YAG passively Q-switched laser using a xenon lamp side-pumping method and based on a graphene saturable absorber was investigated. Firstly, the graphene saturable absorber was successfully prepared by transferring graphene to the Al2 O3 substrate, and its properties such as morphology, structure, and chemical state were characterized. In addition, the characteristics of the Er∶YAG passively Q-switched laser based on graphene saturable absorber were studied. The results show that the single pulse energy increases from 0. 4 mJ to 7 mJ, the output laser single pulse width decreases from 761. 2 ns to 510 ns, and the maximum peak power is 13. 7 kW. The central wavelength of the laser is located at 2 935 and 2 945 nm, and the full width at half maximum (FWHM) corresponding to the main wavelength at 2 935 nm is 1. 535 nm. The beam quality factors along the x and y directions are 4. 45 and 5. 76, respectively. This study provides an effective reference for developing lower cost 2. 94 μm band Er∶YAG lasers with simple and compact resonant cavity designs.