After ultra supercritical(USC) boiler unit is put into commercial operation, some problems often occur including welded joint fracture, heating surface explosion, oxide coating tube-blockage and so on. By comparing the heat load and corresponding materials of various boilers, the early failure and oxide coating exfoliation are analyzed of new type of heat-resistant steels such as T23, T/P92, SUP304H, HR3C, etc. In addition, the countermeasures are proposed, providing references for improving the safety and reliability in manufacture, installation and operation of the USC boilers.