The paper presents optimization of energy and peak power of the pulse oaf laser with a slow passive Q-switch. The excited states absorption (ESA) in absorber is included in an optimization process. The described laser's model provides determination of the optimal values of unsaturated absorber transmission and reflectivity of the output mirror as a function of the normalized initial gain coefficient z and a, characterizing the ratio of the absorption cross- section of the nonlinear absorber to the emission cross- section of the laser medium. In addition, the a parameter has been modified with its value dependent on the magnification M, determining the ratio of the cross-section of the laser beam in the laser medium to the cross-section of the laser beam in the nonlinear absorber. To optimize the passively Q-switched laser the charts and simple analytical formulas, presented in the paper, can be applied. The paper presents also analytical formulas determining the values of laser pulse generation, i.e., pulse duration, its energy, and peak power. As an example, optimization of energy and peak power of the pulse of Nd:YAG laser, with Cr4+:YAG crystal as passive Q-switch, pumped by 100 W matrix of laser diodes was presented. It was shown that for laser energy optimization, ESA slightly changes the value of optimal unsaturated absorber transmission and optimal reflectivity of the output mirror of the laser.