Improving the steam temperature and the pressure of the boiler applied in the thermal power could enhance the coal-fired efficiency and reduce the emission of harmful gases. Due to the dual impact of dwindling fossil resources and an exacerbated global greenhouse effect, it is critical to develop new heat-resistant boiler materials for ultra super-critical (USC) units at temperatures of 650 degrees C and higher. With great thermal conductivity, good fatigue resistance, and low cost, martensitic heat-resistant steel G115, based on P92 steel applied in 600 degrees C USC units, is a promising steel to be applied to this among all candidate materials. This paper introduces the main chemical composition and the microstructure feature of G115 steel, and the research progress in the areas of microstructure stability, creep performance, fatigue resistance, steam oxidation resistance, and industrial pipe production are summarized, with a focus on the role of Cu-rich phase in G115 steel. Finally, some key points on G115 steel are proposed to provide ideas for future research.