A series of experimental tests on the wear performances of assembled metalimpregnated carbon strip rubbing against Ag-Cu contact wire were carried on the highspeed electrical pantographcatenary test system to investigate the influence of joint gap and height difference between the two strips on plough wear and abnormal wear of metro contact line.The test result indicates the height difference between the two strips will cause seriously scratch of the contact wire,which is the main reason for the plough wear of the contact wire,while the joint gap will only cause slightly scratch of the contact wire.The vertical force over 80 N can decrease the wear of the strip notably.When the joint gap is small,it is easier to scratch the contact line and cause plough wear.By analyzing the wear surface morphology of the strip,it is found that there is mechanical scratch on the strip surface when there is height difference between two strip,and the electrical wear and material transformation of the strip are also serious