The double-frequency process based on periodically poled heavily doped MgO∶LiNbO3 is theoretically researched. A first order quasi-phase-matching periodically poled optical micro-structure doped MgO∶LiNbO3 for second harmonic generation with 5.8～7.3 μm period(interval of 0.3 μm), 10 mm length, 10 mm width and 1 mm thickness has been successfully fabricated by applying an external field at room temperature and under ～5.5 kV/mm of the lower switching field. Controlling temperature at about 70 ℃，the experiment on the manufactured optical micro-structure using Nd∶YAG laser with wavelength of 1.064 μm as fundamental frequency is carried to validate the double frequency. About 15 mW 532 nm of quasi-continuous-wave double-frequency blue light output is obtained which is pumped by 920 mW of the fundamental power, corresponding to 1.77 %/W normalized conversion efficiency.