Abstract: The attachment of the DC arc on the anode is usually affected by surface morphology such as protrusions due to ablation or melting deformation. A three-dimensional thermodynamic and chemical non-equilibrium model is used to numerically simulate the effect of artificially assumed surface protrusions on the arc anode attachment. The numerical simulation results show that the arc deflects toward the protrusions on the anode and attaches to them in a constricted mode, resulting in an increase in the temperature of the arc attachment region. The analysis shows that the presence of protrusion on the anode surface changes the electric field distribution, intensifies the degree of thermodynamic and chemical non-equilibrium in its vicinity, further influences the chemical kinetic process of the plasma around it, which is the main reason for the deflection of the arc toward the protrusions and the arc anode attachment in a constricted mode. In order to verify the numerical simulation results, verification experiments are also performed using similar size scale anode protrusion, and the results showed that the presence of protrusion can indeed cause the deflection of the arc and even cause the ablation of the protrusion.