A high power diode-end-pumped Nd∶YVO4 all-solid-state ultraviolet laser was demonstrated under acousto-optic Q-switched operation,which include a stable and high efficient fundamental wave cavity,using type Ⅰ phase-matched LBO as second harmonic generation crystal and typeⅡphase-matched LBO as third harmonic generation crystal.To improve the frequency-tripled efficiency,a 4 f system is used to focus the laser into THG LBO crystal,which reduce spherical aberration of focusing lens effectively.The CW output power of fundamental wave is 15.9 W at the incident pump power of 32.3 W,optical-to-optical efficiency is 49％.The output power of 355 nm UV laser reaches to 1.45 W at 20 kHz repetition rate.By the test,UV laser beam quality factor M2x is 1.6,M2y is 1.56 at the maximum output.