Abstract-In this letter, we have investigated the wavelength tunability and actively Q-switched performance of Tm,Mg:LiTaO 3 lasers for the first time. With a birefringent quartz plate, the tunable Tm,Mg:LiTaO 3 laser was realized, which could be tuned from 1835 to 1995 nm, corresponding to a full-width at half-maximum of 100 nm. Using an AO modulator as an optical shutter, a 244-ns pulse at 1924.2 nm under a pulse repetition rate of 1 kHz was obtained, corresponding to a single pulse energy of 0.47 mJ and peak power of 1.65 kW. We believe it is the highest peak power, which is never achieved in the rareearth-doped ferroelectric crystal lasers.