In this paper, we demonstrate an efficient cavity-dumped Ho:SSO laser linewidth-narrowed by a volume Bragg grating for the first time. When the incident pump power was 19.3 W, the maximum average output power of 6.33 W was achieved at a pulse repetition rate of 100 kHz, corresponding to the slope efficiency of 48.5% and optical conversion efficiency of 32.8%. The pulse width was kept at approximately 3.6 ns. The output wavelength was located at 2100.5 nm with a linewidth of 70 pm. In addition, the beam quality factor M 2 of the cavitydumped Ho:SSO laser at maximum output level was measured to be 1.5 by 90/10 knife-edge technology.