To study the influence of diamondlike carbon (DLC) coating on shaft surface on the load carrying capacity of sliding bearings,the journal center locus and seizure loads of gray iron,aluminum alloy and polyimide (PI) coating bearings with 40Cr steel shaft and DLC coating shaft under both aligned and misaligned conditions were investigated by a sliding bearing test rig.The friction coefficients of different friction pairs were also tested.Results show that compared with the results with 40Cr steel,the friction coefficients of gray iron and aluminum alloy with DLC coating decrease,and the eccentricity ratios of the two kinds of bearings under heavy load decrease.The seizure load of gray iron bearing with DLC coating shaft under aligned condition exceeds 10 MPa,and that of aluminum alloy bearing reaches 7.8 MPa (increases by 1.1 times).The deformation of the two kinds of bearings when seizure happens under misaligned condition increases.Under heavy loads the friction coefficient of PI coating with DLC coating increases,the seizure load of PI coating bearing under aligned condition decreases to 3.6 MPa (decreases by 44%),and the deformation when seizure happens under misaligned condition decreases.