A　high-power　multi-pass-pump　Yb　:　YAG　planar　waveguide　laser　amplifier　was　designed.　The　new　amplifier　adopted　symmetrical　pumping　scheme,　in　which　the　pump　sources　were　symmetrically　placed　on　both　sides　of　the　planar　waveguide.　The　pump　light,　reflected　in　the　planar　waveguide,　passed　through　the　core　multiple　times.　Multi-pass　pump　was　thereby　achieved.　The　factors　affecting　the　pump　absorption　characteristics　were　analyzed,　and　the　relationships　between　the　geometric　parameters　of　the　planar　waveguide　were　determined.　The　planar　waveguide　structure　was　optimized.　The　pump　absorption,　temperature,　and　output　amplification　characteristics　of　the　planar　waveguide　amplifier　were　analyzed　by　a　laser　amplification　model.　The　results　show　that　the　designed　multi-pass-pump　planar　waveguide　amplifier　has　high　pump　absorption　and　optical-to-optical　efficiencies.　When　the　power　of　the　injected　seed　light　is　200　W　and　the　pumping　power　is　10　kW,　its　maximum　pump　absorption　efficiency　is　96.　8%,　with　a　corresponding　amplified　output　power　of　7483　W　and　an　optical-to-optical　efficiency　of　72.　8%.　Meanwhile,　a　good　absorption　uniformity　makes　the　amplifier　less　affected　by　the　heating　effect,　which　is　beneficial　to　obtaining　high-quality　beams.