Abstract: The eye-safe kilohertz repetition rate solid-state laser was developed by using the OPO of unstable resonator. Using pulse LD side-pumping Nd:YAG laser crystal and electro-optical Q-switched techniques, the laser achieved high beam quality of 1.064 m fundamental frequency light. The Ⅱ type noncritical phase-matching KTP crystal was adopted in optical parametric oscillation. In order to get high beam quality, the OPO cavity made use of plane-convex unstable resonator structure. The laser system could operate stably at the wavelength of kilohertz repetition rate 1.57 m. When the pumping current of LD was 125 A and the electro-optical Q-switched repetition rate was 1 kHz, the maximum average output power of 1.57 m laser was 4.67 W and the pulse width of the output laser was 4.3 ns, the power instability of 1.57 m was 3%. The laser pumping threshold was about 45 A.