The short pulse laser characteristics of Nd3+:YAG/Cr4+:YAG diffuse-bonded single piece and the semi-external cavity passively Q-switched lasers are investigated respectively. It is found that the semi-external cavity structured passively Q-switched laser can emit laser pulses with pulse duration less than 1 ns, single pulse energy greater than 1 mJ and peak power higher than 1 MW, much better than the performance of the single piece laser. Using the developed laser and a home-made high resolution fiber spectrometer, a compact LIBS system is set up. The performance of the LIBS system is evaluated in the cases of standard iron alloy samples and the Pb contained liquid samples. Qualitative analysis result and quantitative relationship curve are obtained.