The friction and wear experiment has been done in the crystal surface of Ge(100), Ge(110) and Ge(111) in nanoscale by nano-indenter and Atomic force Microscope. Under heavy load conditions, the grooves appear in all of the friction of three different single plane orientations, and the debris accumulate obviously on the verge of nick. As shown in the friction experiment, the effect of crystal orientation is slight on the friction performance of single crystal germanium. The friction force of single crystal germanium increases along with the increment of sliding velocity. Whereas, with the increment of sliding velocity, severe friction trench damage occurs in the crystal surface, the volume of accumulated debris on the verge of nick and the depth of groove become bigger. Under low load conditions, the friction is stable basically. But with the increment of load, the friction of crystal germanium is of nonlinear growth, and there is a brittle plastic transition from plastic deformation to brittle failure on the crystal surface, causing the brittle stripping of the surface of single crystal germanium and the debris accumulation on the two sides of the groove when the load increases to a certain value