The Shanghai Laser Electron Gamma Source(SLEGS) is a powerful gamma source that provides MeV gamma-ray beams for nuclear science and technology. It was developed as one of the 16 beamline stations in the Phase Ⅱ Project of the Shanghai Synchrotron Radiation Facility. The slant-scattering mode is for the first time systematically employed in laser Compton scattering at SLEGS to produce energy-tunable quasi-monoenergetic gamma-ray beams. The SLEGS officially completed its commissioning from July to December 2021. Gamma rays in the energy range of 0.25–21.7 MeV with a fiux of 2.1 × 10~4–1.2 × 10~7 photons/s and an energy spread of 2–15% were produced during the test. This paper reports the results from commissioning the SLEGS beamline.