Experiments　of　laser　percussion　drilling　were　carried　out　on　nickel-based　superalloy　using　a　modified　pulsed　Nd:YAG　laser　with　adaptively　collimating　output.　Peak　power,　pulse　energy　and　assist　gas　pressure　were　optimized　experimentally.　Experimental　results　demonstrated　that　combination　of　pulses,　focal　position,　the　number　of　pulses　in　the　combination　are　the　main　factors　of　hole　taper.　A　pulse　combination　with　increasing　pulse　energy　is　an　effective　method　to　produce　non-tapered　holes.　Even　negative　taper　holes　can　be　produced　through　increasing　the　number　of　pulses　in　the　pulse　combination.　And　1.1∼1.7　mm　above　the　surface　of　the　sample　helps　reducing　the　taper　of　holes.　Non-tapered　holes　with　diameter　of　480　μm　and　510　μm　were　drilled　on　nickel-based　superalloy　with　thickness　of　1.5　mm　and　3　mm.　Variation　of　hole　diameter　was　about　30μm,　and　hole　taper　was