A　high　stability　and　output　energy　of　wide　band　tunable　intelligence　optical　parametric　oscillator　is　developed　by　which　square　pulse　YAG　laser　in　temporal　domain　pumped.　By　means　of　the　smooth　cavity　dumping,　the　reduction　of　output　loss　compensates　the　photon　decrease　in　cavity.　In　experiment,　we　have　investigated　energy　conversion　efficiency　to　compare　the　Gaussian　pulse　with　square　pulse　and　obtained　the　16.5%　to　34.5%　energy　conversion　efficiency　of　the　optical　parametric　oscillator　by　the　square　pulse　pumped.　©　2000　SPIE.