The　effect　of　the　gain　medium　planar　shear　stress,　induced　by　non-radially　symmetrical　pumping　during　power　amplification　process,　on　the　depolarization　of　radially　polarized　beam　was　analyzed　in　detail.　For　radially　polarized　beam,　theoretical　simulation　had　showed　that　the　non-radial　distribution　of　planar　shear　stress　led　to　the　different　depolarization　in　different　polarization　directions,　that　the　depolarization　of　the　direction　of　45　degrees　and　135　degrees　is　five　times　more　serious　than　that　of　0　degrees　and　90　degrees.　In　the　following　experiment,　the　radially　polarized　seed　beam　with　a　repetition　rate　of　1　kHz,　an　average　power　of　5　W　and　a　pulse　width　of　100　ps　was　single-propagating　double-rod　Nd:　YAG　laser　amplifier.　Each　rod　was　surrounded　by　three　diode-pumped　arrays　with　an　angle　of　120　degrees.　During　the　amplification　process,　the　depolarization　degree　of　radially　polarized　beam　was　6.73%,　which　was　obtained　by　measuring　the　difference　between　the　power　of　the　two　beams　transmitted　and　reflected　by　the　analyzer　TFP.　The　power　of　amplified　radially　polarized　beam　was　15.17　W　with　the　purity　of　89.3%　and　M-2　of　3.95.