A high-power high efficiency picosecond (ps) 355 nm ultraviolet (UV) laser was reported based on the nonlinear optical crystal of type-I phase-matching La2CaB10O19 (LCB) which possesses the characteristic of non-hygroscopicity. The high-power third harmonic generation was successfully achieved from a 1064 nm ps fundamental laser. The maximum output power of 7.81 W of 355 nm UV laser was obtained from 35.2 W 1064 nm ps laser (80 MHz repetition rate, 10 ps pulse width) with optical conversion efficiency of 22.2%. The experimental results show that the LCB crystal has a promising prospect in generating high-power high efficiency UV laser. © (2014) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.