A　theoretical　study　on　the　influence　of　cavity　parameters　on　pulse　properties　of　dual　wavelength　Yb:　YAG　mode-locked　laser　has　been　carried　out.　Using　coupled　rateequations,　the　relations　of　the　small　signal　gain　to　the　cavity　parameters　are　simulated　at　first.　The　calculation　results　are　taken　into　Haus＇s　master　equation　to　investigate　the　effects　of　cavity　parameters　on　the　properties　of　dual-wavelength　mode-locking　pulses.　The　results　show　that,　increasing　the　cavity　length,　output　coupling　rate　and　beam　radius　in　the　laser　crystal　in　a　proper　regime　is　benefit　for　pulse　energies　enhancement,　and　the　pulse　widths　will　be　broadened　very　little.