Abstract: During the induction heat processing of the accumulator shell as made of the 34CrMo4 hot-rolled seamless steel pipe，ring-shaped regular defective hole melting phenomenon occurs at the pipe end. Accordingly the causes for the said ring-shaped hole defect are identified as follows by means of the chemical composition analysis，the observation of both macro-morphology and micro-morphology，and metallographic and SEM analyses of the defect pipe specimen. Due to the effect by the heat conduction effects，at the initial stage of the heating，the pipe end surface temperature is the highest. As the heating rises，and the heating time extends，the area with the highest temperature gradually moves from the surface to the interior，and as a result the temperature in the middle part of the steel pipe wall exceeds the surface temperature，being close to or even higher than the melting point of the metal，which leads to the overburn phenomena like intergranular cracking and hole-melting. It is concluded that properly controlling the induction heating time plays a key role in avoiding hole-melting phenomenon as occurring in the middle part of the pipe wall.