A comparative study of Nd∶KGW and Nd∶YAG laser crystals was conducted under the same experimental conditions in free-running mode and the Q-switched mode, which were pumped by flashlamp at a repetition rate of 1 Hz with a pulse duration of 120 μs. In free-running operation, the slope efficiencys and the extrapolated energy thresholds were determined to be 1.0%,0.44% and 0.54 J, 0.76 J for Nd∶KGW and Nd∶YAG rods, respectively. The slope efficiency of 0.16% and 0.07% for the Nd∶KGW and the Nd∶YAG were obtained in Q-switched mode with the extrapolated energy threshold of 5.9 J and 12.5 J, respectively.