Abstract: With natural surface and blended mud surface,friction properties of sandstone,mudstone's broken surface is tested.It is shown that the strength of surface blended mud is reduced.It is different of the curves of stress-displacement of natural surface and bended mud surface,and the phenomena of mucosity are weakened when the contact surfaces are blended mud.Researching the topography character both fore and after the friction test,degree of roughness and fluctuation of surface are analyzed with statistics theory,and the relation of friction strength and topography character is approached.