We report on a tunable polycrystalline ceramic Er:YAG laser with a total tuning range of 23.1 nm by using a volume Bragg grating. The whole tuning range was composed of three parts, 1614.2 nm - 1621.5 nm, 1629.3 nm - 1635.1 nm and 1639.2 nm - 1649.2 nm. The bandwidth of the output spectrum (FWHM) of the tunable Er:YAG laser was narrowed down to <0.05 nm over the whole tuning range. To our knowledge, this is the widest tuning range so far in this material and it is the first time to report an Er:YAG laser operating at around 1630 nm. In the tuning range of 1629.3 nm- 1635.1 nm, the maximum output power of 1.4 W was obtained at 1633.0 nm with a slope efficiency of 20.9% with respect to the incident power.