A 10-mW 1064-nm dual-frequency laser is designed herein by using a single-frequency laser with a single non-planar ring oscillator and an acousto-optic modulator. The range of the beat frequency is 125-175 MHz. The 1064-nm dual-frequency laser is amplified to a power of 10 W by a fiber optic power amplifier. The 2.26 W intensity-modulated green laser, which corresponds to the maximum frequency-doubling efficiency of 24.5%, is obtained to improve the second harmonic generation efficiency by using two 15-mm-long MgO∶PPLN crystals. The obtained green beat frequencies are 150 MHz and 300 MHz when the frequency difference of the fundamental light is 150 MHz, and they had a 2-min beat frequency stability of 2.7 Hz and 5.3 Hz, respectively.