The high power mode-locking laser system consists of an active-active mode-locking oscillator, a double-pass pre-amplifier, and two single-pass amplifiers. And the fine cavity length adjustment mechanics, single pulse selector, compensation for depolarization, and other key technologies are used. 1064-nm single pulse energy over 500 mJ is obtained, whose pulse duration is 300 ps, and the jitter is ±15 ns with respect to the external trigger. In addition, 532-nm single pulse energy exceeds 240 mJ, whose harmonic generation efficiency is more than 45% by using BBO crystal. And this laser has been used in satellite laser ranging (SLR) system, with pulse shots larger than 2×108.