In　order　to　figure　out　the　effect　of　tool　wear　on　the　material　removal　process　in　bonnet　polishing,　an　experimental　study　based　on　the　comparison　of　removal　characteristics　of　bonnet　tools　with　various　wear　conditions　is　presented.　Before　the　experiments,　the　tool　surfaces　were　measured　using　a　digital　microscope,　and　it　revealed　that　not　only　the　surface　contour　but　also　the　surface　topography　were　changed　by　tool　wear.　For　this　reason,　a　preprocessing,　i.e.,　a　uniformity　controlling　method　for　the　spot　size,　was　proposed　and　validated　to　keep　the　spot　size　constant　using　static　stress　sensor.　Subsequently,　the　comparative　experiments　were　conducted,　and　it　was　indicated　that　along　with　the　increase　of　the　wear　degree　of　the　bonnet　tool,　the　removal　shape　changed　and　the　peak　removal　depth,　peak　removal　in　unit　time,　and　removal　volume　reduced　significantly,　but　the　roughness　of　the　polished　surface　becomes　better.　Based　on　the　results　and　the　analysis,　we　deduced　that　the　probably　causation　for　the　above　phenomenon　is　the　variation　of　the　friction　between　the　workpiece　and　bonnet　tool,　because　of　the　alteration　of　the　tool　surface　topography　brought　by　tool　wear.　Consequently,　the　forces　in　the　polishing　process　were　measured　using　a　3-component　dynamometer,　and　the　friction　coefficient　was　calculated.　The　results　showed　that　the　variation　trend　of　the　friction　coefficient　is　similar　to　that　of　the　removal　volume,　i.e.,　the　removal　volume　and　the　friction　coefficient　of　the　mild　wear　tool　are　basically　the　same　to　the　new　tool,　but　apparently　larger　than　the　severe　wear　tool,　which　demonstrates　that　the　reduction　of　the　friction　coefficient　by　tool　wear　is　one　of　the　most　important　reasons　for　the　decrease　of　the　removal　efficiency.