This paper reports a high power diode pump 5th harmonic generation of Nd: YAG laser system, which could generate up to 300 mW TEM00 mode output with 100 Hz repetition rate at 213 nm. A diode pump module was specially designed for a high efficiency and good beam quality at the fundamental wavelength 1064 nm. An amplifier was set up out of the cavity to boost up the energy level of fundamental wavelength. In order to get high efficiency of the 5th harmonic generation, the cavity of the fundamental wavelength is EOM Q-switched which could generate very high peak power of the fundamental wavelength laser for extra cavity harmonic generations. Finally, 14% conversion efficiency from IR to UV was achieved, which is the highest efficiency in the market to the best of our knowledge right now. 213 nm is a very good substitute wavelength of 193 nm for different UV applications, the system of which is more compact, higher energy, less maintenance and better beam quality than the system of 193 nm.