In　this　paper,　a　low-loss　ridge　waveguide　based　on　the　thin　film　lithium　niobate　(TFLN)　is　successfully　fabricated　using　a　proton-exchanged　wet　etching　(PEWE)　technique,　which　can　result　in　a　much　better　vertical　sidewall　angle　and　improve　the　surface　roughness　to　reduce　the　scattering　loss.　The　average　etching　rate　is　obviously　improved　by　the　structural　defects　and　phase　transition　induced　by　our　modified　PE　process,　and　the　finally　optimized　etching　rate　is　as　fast　as　13.5　nm/min.　The　propagation　loss　of　the　fabricated　straight　ridge　waveguide　is　measured　to　be　4.3　dB/cm　by　using　an　850　nm　single　mode　laser　as　the　light　source.　Meanwhile,　a　Y-branch　waveguide　is　also　measured　with　a　uniform　light　splitting　ratio　of　nearly　1:1.　Furthermore,　this　work　offers　the　route　for　the　manufacturing　of　low-cost　and　high-efficiency　photonic　integration　platform.