The invention provides an electrical control system for automatic welding of a surfacing welding machine. The system comprises a system control PLCA, an upper computer touch screen B, an X-axis motor driving board Q1, a Y-axis motor driving board Q2, a Z-axis motor driving board Q3, an X-axis motor M1, a Y-axis motor M2, a Z-axis motor M3, an X-axis encoder P1, a Y-axis encoder P2, a Z-axis encoder P3, a welding machine system H, an X-axis limiting system X1, a Y-axis limiting system X2, a Z-axis limiting system X3, an axis-back-to-zero system C and a three-axis portal sliding frame mechanism G. By using the system, not only can the automatic operation of surfacing operation be realize, but also the equipment purchasing and maintaining costs can be greatly reduced, and the technical requirements for operators are also greatly reduced.