In this work, an efficient intra-cavity second harmonic generation of green laser in a periodically poled MgO doped LiNbO 3 (MgO:PPLN) bulk crystal using a compact Nd:YVO 4 laser as a fundamental laser source is reported. Different length, different working temperature MgO:PPLN crystals are tested and investigated in the SHG experiments. The maximum output power at 532 nm is 6.2 W at the absorbed pump power at 808 nm of 14 W, the optical to optical conversion efficiencies from 808 to 532 nm and 1064 to 532 nm are 43 and 77%, respectively, the instability in 2 hours is less than 5%.