By　using　femtosecond　laser　filamentation,　the　drilling　of　micro-holes　in　2　mm　thick　polymethyl　methacrylate　materials　in　the　air　environment　is　carried　out.　During　the　experiments,　the　variations　of　the　femtosecond　laser　filament　length　with　average　femtosecond　laser　power　are　summarized.　The　surface　morphology　and　the　diameter　of　the　micro-holes　are　measured　by　scanning　electron　microscopy.　The　hole　dimensions,　the　aspect　ratio　(depth　to　diameter)　and　the　taper　as　a　function　of　laser　average　power　and　processing　time　are　analyzed.　The　results　show　that　with　the　increase　of　the　average　laser　power,　the　diameter　and　the　taper　of　the　holes　increase　obviously,　while　the　aspect　ratio　decreases.　With　the　increase　of　the　processing　time,　the　diameter　of　the　holes　increases,　the　aspect　ratio　decreases,　and　the　taper　of　the　holes　increases　first　and　then　decreases　and　then　increases,　however　it　keeps　an　increasing　trend　in　overall.　©　2017,　Chinese　Lasers　Press.　All　right　reserved.