A high peak power, sub-nanosecond passively Q-switched Nd∶GdVO4 laser with wide temperature stability is presented. The oscillator adopts a flat-concave cavity structure with pigtail coupling of semiconductor laser diode, and takes Cr4+∶YAG as saturable absorber. When the pump absorption energy is 5.9 mJ, the output peak power of the oscillation is 1.5 MW, with pulse width of 600 ps and pulse energy of 0.9 mJ. The efficiency of light to light conversion is 15.4%. The divergence angle is 1.2 mrad. An end pumped double pass amplifier is used and the output peak power of 3.5 MW with pulse energy of 2.1 mJ is achieved. The output laser energies at different temperatures are measured. The results show that the jitter of laser output energy (root-mean-square) is 5% when the temperature is in the range of 20-36 ℃. The laser has compact structure and low power consumption, which can be used as light source for future space laser applications.