The invention provides a jacking positioning device, oil heater piece conveying equipment and an oil heater welding system. The jacking positioning device comprises a jacking frame and a jacking assembly. The jacking assembly is installed on the jacking frame. The jacking assembly is at least partially arranged below a conveying chain of an oil heater piece conveying line in a liftable mode so that an oil heater piece on the conveying chain can be jacked to the preset position above the conveying chain. The problem that the oil heater production efficiency is low in the prior art is solved through the jacking positioning device.