To demonstrate an energy adjustable passively Q-switched laser, a diode laser pumped Nd:YAG crystal diffusion-boned with a wedged Cr4+:YAG crystal is utilized. By changing the transverse pump location of the laser diode on the laser crystal, the initial transmission of the saturable absorber can be flexibly adjusted to achieve the variation of output pulse energy. The experimental result for different crystal length and different pump area are also shown in the thesis. In addition, the multi-transverse-mode output is eliminated to maintain good beam quality by controlling the input power and pump location. For further applications, the 1064-nm PQS laser is utilized to generate a frequency-double 532-nm laser. Finally, the whole set of the green laser is modular in order to be used in actual industrial demand.