The XG-Ⅲ petawatt laser facility with three beams for fast ignition research and strong-field physics applications has been designed and is being constructed.The first beam (referred as SILEX-Ⅰ) is a Ti:sapphire femto-second laser which pulse width is 30 fs, and till now, output power has reached to 330 TW.The other two beams are Nd3+:glass lasers which output energy are larger than 1 kJ and pulse width are about 1 ps and 1 ns respectively.By using the technology of OPA pumped by 800nm femtosecond laser and seeded by super-continuum white light, the three beams are synchronized with each other without jitter time.