The invention discloses a maintenance-free energy-saving on-load capacity-regulating switch and an operation method of the maintenance-free energy-saving on-load capacity-regulating switch. The maintenance-free energy-saving on-load capacity-regulating switch comprises an online filter device, a transmission device and an on-load capacity-regulating switch, wherein the online filer device which is an integral die casting is arranged at the top of the on-load capacity-regulating switch; a filter element is arranged at the top of the online filer device, and an aluminum cap is arranged in the middle of the online filer device; a breather is arranged on the aluminum cap, and a switched motor, an oil inlet pipe and an oil outlet pipe are arranged below the aluminum cap; the transmission device is arranged below the online filter device; the on-load capacity-regulating switch is arranged below the transmission device; and the on-load capacity-regulating switch is formed by vertically arranging a high-voltage contact and a low-voltage contact. According to the maintenance-free energy-saving on-load capacity-regulating switch, the online filter device and an on-load tapping switch are of independently-arranged structures and independently operated, so that the space is utilized sufficiently, the practical applicability is strong, and the installation is convenient, so that the production cost is lowered and the safe operation of a transformer is ensured.