Acousto-optically Q-switched operation of Tm (5 at. %), Ho(0.5 at. %):GdVO4 laser was reported in this paper. The Tm,Ho:GdVO4 crystal was cooled by liquid nitrogen and end-pumped by a 13.6 W fiber-coupled laser diode at 794 nm. Average power of 3.9W was obtained at pulse repetition frequency (PRF) from 10 to 50 kHz, with corresponding to optical-to-optical conversion efficiency of 29 %, and slope efficiency of 35%. The highest energy per pulse of 1.1 mJ in 23 ns was achieved at 3 kHz with peak power of 46 kW.