A monolithic Nd:YLF laser was pumped by a multi-quantum-well laser diode arrary and the linear polorized light was obtained at 1.047 μm with a threshold of 6.8 mW and a slope efficiency of 24%. The maximum output energy reached 6.7 μJ. The peak power of 50 mW was achieved by a gain-switching. Theoretical analysis for the threshold, the slope efficiency and the gain-switching of the solid laser pumped by a laser diode was presented.