The invention discloses an energy-saving and reliable AC electric welding machine. The machine comprises an AC power supply, a first switch, a second switch, a first fuse, a second fuse, a first relay, a second relay, a first capacitor, a second capacitor, a third capacitor, a normally-opened contact switch of the first relay, a normally-closed contact switch of the second relay, a transformer, a welding handle, a first diode, a second diode, a third diode, first to seventh resistors, first to fourth voltage-stabilized diodes, a potentiometer, an one-way thyristor and an unijunction transistor; the first relay is powered off, the first capacitor is connected to a loop of the transformer, and the electric welding machine enters an idle load energy saving state under the current limiting effect of the first capacitor; when a welding part is in contact with the welding handle and after 5 seconds that the electric welding machine is stopped from normal work, the electric welding machine enters the idle load state. With the adoption of the machine, the standby current of a primary coil of the transformer can be automatically reduced when welding is not carried out, and thus the energy consumption of the electric welding machine can be reduced; the electric welding machine has the characteristics of being simple in structure, and reliable in performance during working.