The invention discloses a starting device for a welding machine, and the device comprises a starting seat and a starting head cooperating with the starting seat. The starting seat is provided with a slot, wherein the port of the slot faces upwards. The bottom end wall of the slot is provided with electric connection grooves in a manner of lateral symmetry. The front and rear end walls of the slot are respectively provided with a guide groove which extends laterally. The bottom end of the slot is provided with stopping blocks in a manner of lateral symmetry, wherein the stopping blocks can slide left and right. The front and rear end faces of the stopping blocks are respectively provided with a guide bulged head which extends laterally. The guide bulged heads are disposed in the guide grooves. The stopping blocks are provided with through connection grooves which are through vertically, and the through connection grooves are provided with guide bevel edges. The interior of the starting head is provided with a circuit breaker, and the bottom of the starting head is provided with electric connecting rods cooperating with the electric connection grooves. The front and rear end walls of the slot are provided with lower chutes communicated with the guide grooves in a manner of lateral symmetry, and the lower chutes are slidingly provided with locking blocks.