Abstract: In order to output high beam quality laser from a side-pumped all-solid-state 355nm ultraviolet laser, resonant cavity structure was optimized and intra-cavity double frequency and triple frequency was designed by using the method of intra-cavity beam propagation matrix simulation. Theoretical analysis and experimental verification show that under pump power of 280W and acousto-optic modulation frequency of 40kHz,output power of 355nm ultraviolet laser is 10.58W, pulse width is 20ns and quality factor M2 is 1.3. The results show that side pump intra-cavity double frequency and triple frequency can realize the output of high power ultraviolet laser of approximate fundamental mode. The study has guidance for the engineering of ultraviolet laser.