This　study　investigates　the　fabrication　process　of　Zn-diffused　ridge　waveguides　in　periodically　poled　magnesium-doped　lithium　niobate　(PPMgO:　LN).　A　controlled　variable　method　is　used　to　study　the　effects　of　diffusion　temperature,　diffusion　time,　ZnO　film　thickness,　and　barrier　layer　thickness　on　the　surface　domain　depolarization　and　waveguide　quality　of　PPMgO:　LN.　A　special　barrier　layer　is　proposed　that　can　automatically　lift　off　from　the　sample　surface,　which　increases　the　depth　of　Zn　doping　and　reduces　the　surface　loss　of　the　waveguide.　By　optimizing　the　process　parameters,　we　fabricate　Zn-diffused　PPMgO:　LN　ridge　waveguides　with　a　length　of　22.80　mm　and　a　period　of　18.0　mu　m.　The　above　waveguides　can　make　a　second　harmonic　generation　(SHG)　at　775　nm　with　an　output　power　of　90.20　mW　by　a　pump　power　of　741　mW　at　1　550　nm.　The　corresponding　conversion　efficiency　is　3.160%/W　center　dot　cm2,　and　the　waveguide　loss　is　approximately　0.81　dB/cm.　These　results　demonstrate　that　high-efficiency　devices　can　be　obtained　through　the　fabrication　process　described　in　this　paper.