A research on LD end-pump CW Nd:YAG producing 1 319 nm single-wavelength operation is reported.The oscillation of the wave at 1 064 and 1 338 nm is depressed by selective coating on the output mirror.We obtain 3.11 W cw single-wavelength output power at 1 319 nm under the condition of 26.03 W pump power.In addition,we analyze the conditions to realize 1 319 nm single-wavelength operation and draw a figure which describes the relation between the output mirror transmission at 1 319 nm and the one at 1 338 nm when laser operating single-wavelengthly at 1 319 nm.This figure provides a theoretical guidance to realize 1 319 nm single-wavelength operation.The result of experiment is in agreement with the theoretical result.