A　diode　array　side　pumped　Nd:YAG　thin　disk　laser　was　reported,　and　the　light　distribution　of　doped　crystal　and　temperature　distribution　of　the　radial　were　studied　theoretically　and　experimentally.　The　output　laser　peak　power　of　230　W,　opt.-opt.　efficiency　of　33.5%　and　beam　parameter　product　of　21.6　mmmrad　were　obtained.　The　results　of　experiment　showed　that　side　pumped　Nd:YAG　thin　disk　laser　could　realize　light　uniform　distribution,　and　decrease　temperature　difference　of　radial　significantly.　And　composited　Nd:YAG/YAG　cryatal　could　satisfy　the　requirements　of　side　pumped　thin　disk　laser.　These　techniques　and　methods　could　apply　to　higher　power　side　pumped　thin　disk　laser.