The paper addresses the assessment of the steam-side oxidation behavior of alloy TP347H tubes in supercritical boilers.The high temperature heating surface of supercritical boiler can easily form the oxide scale on the inside surfaces of steam tubes after a period of operation. When accumulated to a certain amount, the oxide scale would exfoliate. It could influence the actuating medium flowing and heat transferring, cause overheating or even the explosion of heating surface. The oxide scale sampled on heat-absorbing surface of alloy TP347H tubes was examined. The oxide exfoliation sampled was studied experimentally by energy dispersive spectrometer and the X-ray diffractometer. The constituent elements and structural features of oxide scale in TP347H tubes were emphatically analyzed. The mechanism of steam-side oxidation and scale exfoliation in the TP347H tubes, as well as its influence factor, were described. It is found that the temperature is one of the most important influences. The measures that controlled the oxide exfoliation on a large scale were brought forward so as to provide a scientific guidance for reducing the oxide scale formation and avoiding tube bursting for over-temperature.