Abstract: The characteristics of cathode spots arc were introduced in this paper.Considering the theoretical models and the new experimental results,the mechanism and process of the cathode arc discharge were analyzed systematically:electron explosive emission model,thermionic field emission theory,Mackeown formula in collisionless layer at cathode,and spots motion model in a magnetic field.In the end,the mechanism of the pressure effects on the spots motion and the anode spots characteristics were discussed.