Aluminum　nitride　(AlN)　films　are　prepared　on　Si　(100)　substrates　by　pulsed　direct　current　magnetron　sputtering.　The　effect　of　sputtering　power　on　the　crystal　quality,　residual　stress,　surface　morphology,　and　optical　properties　of　AlN　films　is　comprehensively　studied　using　X-ray　diffraction　(XRD),　Fourier　transform　infrared　spectroscopy　(FTIR),　atomic　force　microscope,　and　ellipsometer.　It　is　found　that　the　AlN　film　quality　is　strongly　impacted　by　the　sputtering　power.　When　the　sputtering　power　increases　to　3　kW,　the　full　width　at　half　maximum　of　the　AlN　(002)　rocking　curve　decreases　to　2.66　degrees.　And　the　film　crystal　quality　does　not　change　significantly　when　the　sputtering　power　exceeds　3　kW.　Fourier　transform　infrared　spectrum　analysis　shows　that　with　increasing　sputtering　power,　the　compressive　stress　of　AlN　films　first　increases　and　then　decreases.　The　high　sputtering　power　also　results　in　smoother　surface　and　better　optical　performance　for　the　AlN　films.　This　work　can　serve　as　an　important　reference　for　growing　high-quality　AlN　films　on　cost-effective　silicon　(Si)　substrates　via　sputtering,　which　can　facilitate　the　development　and　commercialization　of　III-nitride　based　photonics　and　electronics　on　AlN-on-Si　substrates.