A laser modulation and amplification system is designed to meet the demand of long-range space optical communication, which uses the high-speed semiconductor laser to integrate electro-absorption (EA) modulator as a seed source. Two optical fiber amplifier technologies are used. The erbium-doped fiber amplifier (EDFA) and single-mode semiconductor laser pumping are used in the first-level; erbium ytterbium co-doped fiber amplifier (EYDFA) and 2-4 multimode fiber laser pumping with good temperature characteristics are used in the second level, and the control method is automatic gain control. The experimental result shows that the modulation rate achieves to 10Gbps, and the output optical power achieves to 5W.