The continuous variation of workpiece inclined angle of ca rbon fiber reinforced polymer (CFRP) curved surface structures could result in machining defects such as burrs and delamination. In order to investigate the in fluence of workpiece inclined angle on the machinability of CFRP curved surface structures， down milling is conducted on CFRP laminates with various inclined an g les by using a diamond coated cemented carbide tool. The milling forces in diff e rent coordinate systems and machining surface deficiency are studied. The resul ts show that the sectional area and average cutting thickness by pre tooth decre ase， and equivalent depth of cut increases with the increase of workpiece in clined angle. However the volume of material to be removed by pre tooth always keeps c onstant. The milling forces in machine coordinate system also keep constant， whi le the milling forces in workpiece coordinate system increase along the directio n of work piece thickness and decrease along the direction of workpiece length. T he defe cts of workpiece profile and finished surface get severe with the increase of wo rkpiece inclined angle. The fiber bundles will bend instead of rupture and crack grows into the workpiece along the fiber direction. The numbers of damaged plie s also increase with the increase of workpiece inclined angle.