By using an active-passive mode looked Nd3+:YAG laser and avalanche transistor absorption single pulse slicer, amplifier, frequency doubler, and a frequency mixer, 30 ps single laser pulse at 355 nm was obtained. It was used as the pump source of a type I noncritically phase-matched LiB3O5 optical parametric generator. Under the precise control of crystal temperature, 415.9～482.6 nm tunable blue-viole laser with 0.15 nm linewidth has been achieved. The highest parametric energy conversion efficiency has been up to 37.6%, which leads to the picosecond laser output with energy of 6.33 mJ and peak-power of 211 MW.