In this paper, we present a diode side-pumped Nd:YAP laser based on TEC temperature controlling that can produce single pulse energy of 12.00 mJ and 11.45 mJ of 1.34 μm output under the flat-flat cavity and flat-concave cavityat at repetition rate of 20 Hz. A BBO crystal was used as E-O Q-switched crystal and there was no polarizer in the resonator. The 38ns pulse width of 1.34 μm was obtained with a repetition rate of 20 Hz under the flat-flat cavity. The output characteristic of 1.08 μm was also experimentally researched and the largest single pulse energy of 28.5 mJ and pulse duration of 27 ns was obtained at a repetition rate of 20 Hz under the same flat-flat cavity.