The electric field poling was used to achieve the periodic poling Z cut 1 mm KTiOPO 4 crystal (PPKTP). The grating period inverted was 9.0 μm and the interaction length was 3 mm in the crystal. By using a CW Nd∶YAG laser as a fundamental wave at 1.064 μm, input power in PPKTP of 900 mW, 22 μW green SHG at 0.532 μm was obtained at 32 ℃. The conversion efficiency of SHG was 0.0024%.