The invention discloses an arc power supply which comprises a high-voltage isolation transformer, of which a primary winding is connected with single-phase AC inputs, a first secondary winding is connected with a first rectifying device, and a second secondary winding is connected with a second rectifying device. The first rectifying device is connected with a constant-current charging device; a first capacitor, a third capacitor and a first circuit structure are connected in parallel between the two output ends of the constant-current charging device, wherein the first capacitor is a super capacitor; a second capacitor and a second circuit structure are connected in parallel between the two output ends of the second rectifying device; and the first circuit structure is connected with the second circuit structure in series through an output loop. Compared with a conventional arc power supply of a current transfer circuit, the arc power supply is more flexible in circuit control, can quicken transfer of the current during current transfer, and can quicken recovery of the current during current recovery; and during pit digging, energy can be transferred and stored to the capacitors, and thus pit-digging efficiency is improved.