A compact pulse side-pumped Nd： YAG laser by high-temperature laser diode arrays was designed. The operating temperature of pumping source was controlled at 60℃ by the semiconductor refrigerator， the emission center wavelength was 808nm， and the spectral line width was 4.12 nm. Dynamic temperature field distributions of the pumping source in 60s at 40℃、50℃ and 60℃ were simulated. Two φ5 mm×50 mm Nd：YAG crystals with 1.0at.% Nd³⁺ doping concentration were used as the laser gain medium. The crystal of potassium dideuterium phosphate was used forelectro-optic Q-switching. With a pump source voltage pulse width of 250 $\mathrm{\mu }\mathrm{s}$ and the repetition frequency of 20 Hz and 1 Hz， output pulsed energy of 230 mJ and 246 mJ were achieved corresponding to the pulse durations of 8.4 ns and 7.8 ns. The beam divergence was 1.6 mrad. The total electro-optical conversion efficiency of designed Nd： YAG Q-switchedlaser was greater than 4.6%.