A tunable continuous-wave (cw) Nd:YAG laser using a birefringent filter (BF) was performed at six different laser wavelengths of 1319, 1334, 1338, 1341, 1353 and 1356 nm based on the 4F3/2–4I13/2 transition. A highest output power of 4.64 W was achieved at an emission wavelength of 1319 nm with a slope efficiency of 29.8% with respect to the absorbed pump power. Moreover, by adjusting the rotation angle of the BF, a cw simultaneous dual-wavelength Nd:YAG laser operating at 1353 and 1356 nm was also demonstrated for the first time. At an absorbed pump power of 17.8 W, the maximum output power obtained at 1353 nm and 1356 nm is 262 mW and 520 mW, respectively.