The invention relate to a forging method of a forge piece for the safe end of a reactor pressure vessel, belonging to the technical field of forging. The forging method comprises the following steps of: selecting a proper steel ingot; repeatedly upsetting-drawing the steel ingot at the temperature ranging from 1180 DEG C to 900 DEG C so that a forging ratio is not less than 4; and then sequentially carrying out property heat treatment and machining after the heat treatment to obtain a supporting seat forge piece. The forge piece for the safe end of the reactor pressure vessel, which is manufactured by using the forging method, has actual grain size finer than that a third grade and various property indexes reaching the standard requirements of a Radio Chemical Centre (RCC-M) and an American Society for Testing Material (ASTM), ensures the utilization requirements of the forge piece for the safe end of the reactor pressure vessel in a nuclear power station, greatly enhances the safety and the reliability of the forge piece and meets the technical requirements of such products.