A laser-diode (LD) pumped Nd:YVO₄ all-solid-state 355 nm continuous-wave (cw) ultraviolet laser with intracavity frequency tripling and efficient output was achieved by optimization design.By considering influence of the thermal lens effect of the Nd:YVO₄ crystal,mode matching,phase matching et al on laser output power,a plate-concave cavity was designed finely.In cavity,the KTP crystal was used for second harmonic generation (SHG) of the fundamental 1 064 nm to generate 532 nm radiation,and the LBO crystal was used as a sum frequency (SM) of the 1064 nm radiation and the 532 nm radiation to generate 355 nm radiation.The cw 355 nm radiation of 6.4 mW is obtained with the pump power of 3 W.In comparison with the fold-cavity,the linear cavity has many advantages of more compact,easier for adjusting,and higher output power.