Abstract:In this paper, a diode-pumped Q-switched Nd∶GdVO4 laserwhich produced ultraviolet output at 266nm by usingBBO crystal single pass fourth harmonic generation is reported. When the incident pumping powerwas 12.5W, we obtained average output power of 196mW at 266nm, the frequency conversion from 1064nm to 266nm is 10. 1% ,and green2UV energy conversion efficiency is 30. 1%.