Hot upsetting process for cast ingot with large height to diameter ratio for ultra large ring forging

The invention relates to a hot upsetting process, in particular to a hot upsetting process for a cast ingot with a large height to diameter ratio for an ultra large ring forging. The process is characterized by comprising the following steps of: 1) hanging a heated high-temperature cast ingot with a large height to diameter ratio on a lower female die; 2) adjusting the position of an upper male die so as to ensure that the central line of the upper male die is coincided with the central lines of the cast ingot and the lower female die; 3) driving the upper male die to move downward by using a power mechanism; 4) further moving the upper male die downward so as to continuously decrease the height to diameter ratio of the cast ingot; 5) reversing the cast ingot which is in a contact molding state by hot upsetting, replacing the lower female die by using a flat plate die and further lowering the upper male die; and 6) replacing the upper male die by using a flat plate die and further lowering the upper male die