Using Q-switched rate equations, the relationship among the optimum reflectivity, maximum pulse energy, largest peak power, pulse width and the dimensionless variable z was analyzed, and the influence of the condition of different cavity roundtrip dissipative loss, cavity gain and inversion reduction factor on actively Q-switched pulse parameters in Nd:YVO₄ and Nd:YAG was also analyzed, respectively. The modeling results indicate that the optimum reflectivity and pulse width decrease with the increase of cavity roundtrip dissipative loss, and the maximum pulse energy and largest peak power decrease with the increase of inversion reduction factor which affects maximum pulse energy and largest peak power greatly. One can make the Q-switched pulse parameters embodied through the certain value of z.