The Q-switching performance in a folded resonator containing prism reflectors is analyzed. It is shown that the performance of the Q-switch in a folded cavity is affected by its configuration. A variety of configurations are compared theoretically. The transmissivities are calculated when the Q-switch is turned on and off, respectively. The effects of the misalignments of the prisms are also calculated. The Q-switch in a folded resonator with prism reflectors is optimized. With the optimal Q-switch, the laser system is more compact and stable. The effects of the misalignments of the prisms on the Q-switching performance are reduced by using optimal Q-switching configuration.