In order to manufacture a pulse single-frequency laser with master oscillator power amplifier(MOPA) structure used for laser coherence imaging, the properties of acousto-optic Q-switched pulse single-frequency 1 064 nm laser used as MOPA laser seed, and properties of extra-cavity double frequency green laser were studied in the paer. 1 064 nm pulse laser output with more than 20 ns pulse width was realized by means of acousto-optics Q
-switch, and single-frequency running was realized by means of loop cavity and etalons with different thickness. The linewidth of 1 064 nm and 532 nm pulse lasers were studied. The experiment results show that there is almost complete coherence in all of the pulse width;1 064 nm pulse single-frequency laser with 28 nm pulse width and 6.5 kW peak power and 532 nm laser with 20 ns pulse width and 0.5 kW peak power are obtained respectively. The efficiency of extra-cavity double-frequency is about 5.6%. The effect of laser pulse reduction by extra-cavity double-frequency is also validated by experiments.