The　stability　of　the　higher　output　power　with　high-quality　beams　is　very　important　parameter　in　material　processing.　This　paper　presents　using　the　S　parameter　and　Gauss　beam　parameters　matching　to　design　efficient　resonant　cavity　of　two-rod　Nd:YAG.　The　fundamental　mode　beam　radius　in　rod,　fundamental　mode　beam　radius　on　the　mirror,　beam　quality　factor,　and　the　value　of　the　degree　of　the　symmetry　of　the　TEM00　mode　volume　as　a　function　of　the　between　neighbor　rods　distance,　laser　rod　end　face　to　mirror　distance,　and　input　power　are　simulated.　The　design　method　of　resonant　cavity　is　illustrated　and　compared　with　previously　published　experimental　measurements　for　different　pump　power　and　the　length　of　the　cavity　parameters　and　a　good　agreement　has　been　found.　©　2014　Elsevier　GmbH.