The　experiment　results　of　high　peak　power　lamp-pumped　pulsed　Nd:YAG　laser　adopting　symmetrical　parallel　plane　cavity　are　reported.　Base　on　the　rate　equation,　the　expression　of　single　pulse　energy　of　pulsed　Nd:YAG　solid-state　laser　is　derived　with　the　simulated　optimum　transmissivity　and　maximum　output　energy.　The　optimal　parameters　are　obtained　by　the　experiments,　and　a　high　peak　power　lamp-pumped　pulsed　Nd:YAG　laser　is　developed　with　the　results　of　theory　simulating　and　optimal　experiments　being　consistent　with　each　other.　When　the　laser　works　under　800　V　voltage,　2　ms　pulse　width,　it　outputs　laser　with　energy　of　60　J,　high　peak　power　of　30　kW　with　beam　quality　M2=5.9,　and　the　total　electro-optic　efficiency　of　3.3%.　When　it　works　under　800　V　voltage,　1.5　ms　pulse　width,　the　maximum　output　average　power　is　405　W.　The　6　mm　mild　steel　and　4　mm　stainless　steel　were　cut　by　the　laser　with　the　2　ms　pulse　width,　6　Hz　frequency　and　30　kW　peak　power.　The　cutting　speed　for　4　mm　stainless　and　6　mm　mild　steel　is　1　mm/s　and　1.5-2　mm/s,　respectively.